When I read te augmenticist in the ITS, i dont know that if the explorer has the Physical perfection Talent, do the Implant systems's bonus stack with it?

forEX: If the explorer has a bionic heart, wich gives +1 ARMOR to body, is it stacks with the Phys. Perf. Talent? And what about the subskin armor? 

If the augmenticist has the Tech-Use skill - and I'm shure he/she has ;) - can he fix himself with Tech-Use test? Like some kind of self medication…

I see no reason why it shouldn't

The armor will stack with whatever other armor layer you have.

But to be capable of healing his own wounds it's a matter of logic.

The character was lightly hurt, yes he could fix it, it is not to painfull and the work will be on the surface.

The character had been heavly damage, then why not try but my guess would be -30 to healing or tech use test due to pain, blood and a real diffficulty to look inside his own belly.

Critical damage would prevent anykind of self healing beside to take in hand this strange red leacking tube call artery and press it untill blood stop going out.