Yes. From the sidebar "Chapter Advances and Deathwatch Advances", page 57:
"Deathwatch-specific Advances can be selected by any Deathwatch Space Marine of the appropriate Rank, and Chapter-specific Advances can be selected by any Space Marine from that Chapter of the appropriate Rank."
When I was running DH, the combat balance point I looked at was average PC's T, Torso AV, and primary weapon damages and pen's in ranged and melee. Used 5.5 per die, rounding up at end, then multiplied by total number of PC's.
If the difference between average damage+Pen and opponent's T+AV is significantly different between sides, the battle will tend to be similarly lopsided.
EG: PC's average Toughness is 40... so T=4. Average torso armor was 4. Weapon damage was averaging 8 (1d10+2), with Pen 4.
NPC side had T6 and AV8, average damage 7 (1d10+3), pen 0...
PC Side was 8+4 vs 6+8, for -2
NPC side was 7+0 vs 8, for -1.
Now, it has to be shifted to positives; move both up the same amount so the lower is +1. In this case, PCs 1, NPC's 2. Now multiply by the numbers. I had 7 PC's, and used 4 NPC's... for 7 and 8. Then multiply by average skill as a percentage... PC average was 45, NPC was 33, for 7*0.45=3.15 and 8*0.33= 2.64. It's clear the PC's have an advantage, but a very weak one... and since in the initial stage, both were negatives, it's going to involve a lot of armor staging.
Best Answer
There's been some important errata to how psy powers work, which is good, because the book's rules are actually somewhere between "unclear" and "contradictory" in several areas.
The most important thing to know is that the example is wrong, wrong, wrong, and should be wholesale disregarded.
The other important thing to know is that all Focus Power tests are made at a difficulty of Challenging (+0).
Also, note that you get +5 to your Focus Power test per point of effective Psy Rating - "effective" meaning "including modifiers for Fettered or Push". (Push provides +3 Psy Rating, and thus +15 to your check.)