1. Only lowers prices, so only worth if you know you will contact him frequently. Which got a bit meaningless in D:OS2 because there are no turn back possibilities between acts like in the first game.
2. Should not be affected by strength, only by telekinesis itself.
3. I hardly ever used sneak in combat. It is on one hand a broken mechanic in combat, because if all your fighters manage to sneak, AI will just freeze, because they have no target. And secondly it does not make much logical sense, to be able to just disappear from sight, standing behind the guy, you just backstabbed before.
Guerilla means suprise attack, therefore for me guerilla was always meant for opening a fight with a huge bang.
4. They get some prebuilt stuff, though sometimes those seem to bug. After Act 1 you can respec them anyhow though.
