I can't answer all your questions, but I have an airwolf about 1 month old, It came with mk5 silencer so tac should as well - very quite.
Battery charge lasts ages, best to charge regularly every month. The battery may need replacing after 2-3yrs I guess. This is my third electric Daystate - no probs to report.
My wolf is gave me 400 shots before I noticed drop off at 40yds from 400cc bottle and 200bar fill - way more than expected.
Mand
Airwolf, Prosport, GinB HW98, LGU, HW100T, Theoben Grand Prix:- all .177