I placed Pyromaniac as advised even though I was not convinced by its efficiency as it was triggering too rarely to rely on it.
Social skills are copy paste from Omni build (Still not sure how to raise it efficiently), are they correct values? It is rather low investment in number of points.
What do you think about this version? Do you see rooms for improvements?
I was also thinking that few points in trap might be useful for some fights> it means 56 points to reach 75 with belt and knife. what do you think? or simple bear trap are far enough as with 3 STR no big carrying possible.
You shouldn't feel the need to take Pyromaniac if you don't want to. It's very good, but psi is very, very powerful and can do just fine without such extreme optimization. The values Omni has are the correct values for a patient min/maxer. With all the right gear, they'll be capable of getting buffed to the necessary thresholds. For someone who doesn't like such extreme measures and would rather just walk around ready at all times, then they are not high enough.
Room for improvements in your new build? Yeah, several. But you've clearly shown that you aren't interested in the level of ridiculous min/maxing that can be achieved by really squeezing a build tight. What you've got will get you through the game just fine. If you really aren't bothered by all the loot you're going to leave behind by not being able to pick and hack locks, then you'll be fine. Me, I'd have an absolute fit - I gotta get them lewts!
Plain bear trap is fine. With the synergy from your Mechanics, you'll even be able to place MKI frags, and with the jackknife, MKI HE as well. Since you'll have so many abilities available by the time you reach mid-levels, the low-level explosives will be enough. And the one fight that's basically designed to show off the maximum potential of traps works just fine with plain bear traps if that's all you've got.
are there any other sources of psi cost reduction?
Like hilf says, there may be some. But I'd hate to spoil the fun of discovering the stuff in the game. Know that there's cool stuff; that should be enough to whet your appetite. Then go chow down on this excellent expansion =)