1) Not sure about aftermarket triggers. I have kept mine stock, and it's ok.
2) Suppressors. My dad's 7.62SD caused so much back pressure the rifle malfunctioned. With my shorter 7.62 SDN-6 there's no problem. I suspect my rifle is over-gassed. Need to but some new gas control screws and fix it, but I've been too lazy.
3) It will love 168 gr. match ammo. Mine shoots VERY well with Federal 175 Gold Medal match in .308. It also shoots well with 145 privi partisan 7.62x51 ball ammo; that's what I use most of the time. 1-1.25 MOA with the Gold Medal match is the norm. I use a Leupold Mark 4 3.5-10 scope. I'm sure with another trigger and a better shooter it would do even better.
4) I bought about 15 factory mags for it. They all work just fine. Unless you have another .308 that uses the SR-25 pattern mag, just stick with factory ones.