This feat is notorious for its poor wording. The “+100%” phrasing is completely unique within D&D 3.5e as far as I know, for example. Ultimately, I can’t imagine any other interpretation here than adding again the number subtracted from your attack rolls, and it does have the nice feature of specifying the “normal” damage from Power Attack which means that features like the frenzied berserker’s supreme power attack that already give one-handed weapons 2:1 returns don’t get doubled to 4:1, but instead go to the 3:1 you would normally expect from D&D’s multiplication rules.
But then there is the line you haven’t quoted:
If you use this tactic with a two-handed weapon, you instead triple the extra damage from Power Attack.
No bizarre “+100%” in sight! But also we have lost the useful reference to “normal” and now it is multiplying “the extra damage from Power Attack,” whatever that is for you. This is going to get us in trouble, you can just tell already.
So you are tripling the extra damage—not tripling the penalty applied. The problem here, well the first problem here, is that “the extra damage from Power Attack” is “twice the number subtracted from your attack rolls” when attacking two-handed. Worse, since “the extra damage from Power Attack” is calculated as twice the penalty, but isn’t itself subject to any multiplier, arguably the repeated-multiplication rules don’t apply, and that gets you a 2×3=6 rather than 1+(2−1)+(3−1)=4. So instead of 2:1 returns on Power Attack, you get 6:1 returns on Power Attack. Or maybe you get 5:1; it’s impossible to say since it’s worded so poorly. Plus, ya know, I suspect what they meant to do was give you 3:1 returns, but of course they didn’t say that.
And that would combine quite nicely with, say, the supreme power attack feature of the frenzied berserker, who was getting 4:1 returns to begin with. Now they’re arguably getting 8:1.
On top of those issues, this is only the Power Attack bonus damage. The result is added to the rest of your damage, and that gets you your full damage... which might be multiplied again, e.g. with valorous. This effectively multiplies your multiplier, which is exactly what the multiplication rules try to avoid, but since two different things are being multiplied, the multiplication rules don’t actually come into play.
So for the example: 2d6+1 damage from the weapon itself, +6 for Strength, and the −6 attack penalty for maximum Power Attack results in double that for +12 damage from Power Attack without Leap Attack. Thus 2d6+19 is the baseline for all interpretations, and valorous doubles that for 4d6+38.
With the 6:1 returns, we are instead looking at Power Attack bonus of +36 (six times the penalty, triple “the extra damage from Power Attack” which would have been +12). Using 5:1 brings that down to +30, which is somewhat better, but not, ya know, great, when what they probably meant was +18. Note that +36 is nearly what valorous was giving the entire attack before. Now with valorous, we’re looking at a total of 4d6+66—of which, 52 comes from Power Attack.
It may not be a bad idea to try to eliminate the multiplication of a multiplier here through houserule, but note that the Power Attack bonus damage isn’t the only case of this: the bonus damage due to Strength also has a multiplier, +1½×, which is also being doubled by valorous. This, unlike Leap Attack, has strong precedent in the rules. The “fix” would be to apply the multiplication rule individually to all sources of damage, like so:
\begin{array}{r}
2 \times ( && 2\text{d}6 && +1 && +1\tfrac{1}{2}\times 4 && +3\times 2\times 6 & ) \\
= && 2\times 2\text{d}6 && + 2\times 1 && + 2\times 1\frac{1}{2}\times 4 && + 2\times 3\times 2\times 6 \\
= & [1 \\
&& +\left(2-1\right) \\
& ] & \times 2\text{d}6 & +[1 \\
&& && +\left(2-1\right) \\
&& & ] & \times 1 & +[1 \\
&& && && +\left(2-1\right) \\
&& && && +\left(1\frac{1}{2}-1\right) \\
&& && & ] & \times 4 & +[1 \\
&& && && && +\left(2-1\right) \\
&& && && && +\left(3-1\right) \\
&& && && && +\left(2-1\right) \\
&& && && & ] & \times 6 \\
= && 2\times 2\text{d}6 && +2\times 1 && +2\frac{1}{2}\times 4 && +5\times 6 \\
= && 4\text{d}6 && +2 && +10 && +30 \\
= && && && && 4\text{d}6+42 \\
\end{array}
But this is very-definitely a houserule, and I’m not convinced that it is good (I mean, good luck calculating that for every attack!), even though it “enforces” the idea that you’re not supposed to get to mulitply multipliers.
The Round in Steps
The fighter employs the feat Power Attack (PH 98) before taking actions to suffer a -6 penalty to attack rolls and gain a +6 bonus to damage with 1-handed weapons and a +12 bonus to damage with 1-handed weapons wielded in 2 hands and 2-handed weapons. This is not an action.
The fighter takes a full-round action to make a charge. During the charge the fighter makes a Jump skill check (DC 10 if the fighter first moves in a straight line at least 20 ft. otherwise DC 20) to clear at least 10 ft. of distance--ending his movement in a square that threatens the foe--, to get the benefits of the feat Leap Attack (CAd 110).
Instead of making an attack at the charge's end, the fighter attempts a bull rush. Because of the charge the fighter gains a +2 bonus on the bull rush attempt. Because of the attempted bull rush rather than the attack, the Shock Trooper (CW 112) feat's tactical maneuver heedless charge is unused, and the benefits of the feat Leap Attack don't apply.
Using the Shock Trooper feat's directed bull rush tactical maneuver, the fighter (presumably) successfully bull rushes the charge victim into another nearby foe. Using the Shock Trooper feat's domino rush tactical maneuver, the fighter makes trip attempts against both foes.
It's up to the DM whether the tactical maneuver domino rush permits the fighter to make trip attempts against creatures he doesn't threaten. The tactical maneuver seems intended to allow that (knocking foes into each other and proning them after they collide), but nothing in the tactical maneuver says that's allowed, so it may default to the trip rules, which don't permit tripping creatures one doesn't threaten. A weapon with sufficient reach may be needed if intending to launch foes then trip them. Ask the DM.
If a trip attempt is successful and the foe remains within the fighter's threatened area, the tripped foe is subject to the fighter's free attack from the feat Improved Trip (PH 96). Each attack the feat Improved Trip generates gains the benefits of the feat Power Attack.
The feat Leap Attack requires a charge be ended threatening the charge's target and that attack at the charge's end gets the listed bonuses. The sentences aren't discrete, and can't be read individually, and the feat says so ("This attack [the one at the charge's end] must follow all the normal rules for using the Jump skill and for making a charge").
The Shock Trooper feat's tactical maneuver heedless charge suffers the same way: "To use this maneuver, you must charge and make the attack" at the charge's end, and if the fighter doesn't make the attack, making instead a bull rush attempt, the heedless charge tactical maneuver can't be used.
Extra attacks generated as results of charging (such as those made as a benefit of the feat Improved Trip) just aren't the attack at the charge's end, even though the attacks are generated after the charge occurs. Those extra attacks from the feat Improved Trip don't get the benefits of the feat Leap Attack and the tactical maneuver heedless charge.
The feat Shock Trooper essentially lets a character do his choice of crazy things on a charge: either pinball his enemies or deal damage while endangering himself. He can't, using that feat, do both.
(This sequence is unaffected by the Elusive Target (CW 110) feat's tactical maneuver cause overreach and the feat Robilar's Gambit (PH2 82). Those feats function normally.)
Best Answer
RAW, no, Valorous Charge applies only to the attack made at the end of a charge. RAW, pounce gives you a full-attack after that attack.
But as described in that answer, basically no one ever plays it that way. Everyone plays pounce as replacing the attack on the end of a charge with a full-attack. And then we get into a conundrum: do all those attacks still count as being “used in a charge” when we pounce?
For the purposes of optimization discussion (which tends to assume favorable DM rulings as part of the optimization game), the answer is yes. This is part of what makes the Übercharger (though many other things are also being used, most of which are sadly pretty explicit). In my experience, most of the D&D-discussing Internet accepts that this is how things work (many of them think it’s RAW), and then simply just choose not to do that and advise others not to do that since it’s bad for the game. Knowing how an Übercharger works can be useful, since you can make a partial-Übercharger with power levels appropriate for your own game.
But for myself, I tend to actually like to run pounce as-written. Yeah, it means an extra attack, but it makes the whole thing a lot cleaner and clearer. If you really dislike that, you can always do something like “the first attack” or “the first successful attack” gets those benefits, and the rest do not.