The truth about these numbers is much more mundane. Simply put, the way the abilities are coded, all of the green numbers are variables.
For Runes
Runes used to have quality levels, with each successive level of rune increasing the efficacy of the skill. This is why runes like Arcane Torrent's Cascade list "a 100% chance", instead of saying "whenever" or "always" -- if you used a lower level rune, it wouldn't be a 100% chance.
For Abilities and Passives
For abilities, the thinking is mostly the same, though the rationale is different. Essentially, by designing the abilities in the way that they did, they've made it very easy to tweak and balance the individual abilities against each other.
Consider, if you will, Bolas Shot.
Notice which values are in green: The hatred generaiton, the delay, the initial damage, the splash damage, and the splash range. Now imagine that Blizzard determines bolas shot to be horribly, horribly overpowered. They have to nerf it. What do they change? Well, because of the way they built the game, they already have 5 "knobs" to tweak in an attempt to better balance it - the five variables in green. Even when one of the green values isn't affected by any of the five runes, it's still useful as a tuning mechanism.
This happened in beta all the time - the balancing patch notes would always tweak the green values, and leave the rest of the ability untouched.
There is also a subclass of skills and abilities which have the green text because they scale with level.
Most healing abilities are this way. In these cases, the text is green to signify that the value is not constant (because, again, everything in green is a variable), and is used instead of listing a formula (which would be constant, but would be bothersome to calculate manually each time it changed).
Even here, the underlying formula can be changed, with the same results as tweaking the formula in one of the non-scaling abilities above.
I'd bet on the templar, because all of the four ability choices provide tank-like abilities at will. His taunt ability will keep enemies off you for 5 seconds.
Then, as soon as they hit the templar, his Intimidate skill will slow them down by 50%, making it easy for you to get out of range in case they target you again.
His Charge ability will enable him to intercept enemies that attack you, and stun them for 3 seconds in an AOE radius of 15 yards, giving you time to get out of range.
And last but not least, his Guardian ability will make him attack enemies for 300% weapon damage and stun them for 5 seconds if they attack you and you happen to be on low health. As a bonus, he heals you when he uses the ability, and also gives your character life regeneration for a limited amount of time.
Best Answer
All followers can Retrain their skills at any time for free.
The skills I use on mine are Charm, Powered Armor, Erosion and Mass Control. I chose Mass Control to have fun seeing big monsters turn into chickens, as this was a non-WD character - however as a recommendation, I'd actually suggest Focused Mind at that level.
Charm can be very useful in situations where the lead monster of a pack suddenly stops and turns around to beat its buddies, in a narrow corridor - thus buying extra time to spam AoE distance attacks. Its alternative, Forceful Push is something I have not tried yet, could be useful if the followers really do full weapon damage on using their specials (normally they do a pitiful fraction like 12.5%)
Powered Armor helps with all attacks not just non-projectile; and also a lot of 'projectile' attacks can't be reflected, I believe this is the generally superior choice for this slot over Reflect Missiles, unless you want to micro and switch them based on area.
Erosion will greatly help with dps in some situations and is useful for single enemies as well as for groups, and has a shorter CD than Disorient.
Focused Mind is an AoE aura adding 3% IAS. Blizzard even had to nerf IAS so you know its a good stat ;). The alternative of Mass Control is not as helpful, I consider it more of a novelty factor.