Questions about suspension drop

To lower the car you don't need new bump stops and such. You do need a stuts/shocks that work with lowered springs and cc plates to keep a good alignment. Certain cars bump steer more than others. My old 04 with sportlines did no bump steering what so ever, but my current 98 with a pro kit bump steers like a mofo (new steering componets and still does it). So you won't know there till you get the parts installed. I have no clue what ball bearings you would be talking. Ball joints maybe? If so preventative matience is always a good thing, plus your right there and have to get it aligned anyway, so might as well.

All gt's have an 8.8 with limited slip (posi). Odds are if yours is peg legging if its not ever been touched. You need a new clutch pak for it. No need to upgrade to 31 spline till you start making actual power (11 sec range power). Stock 28 spline is just fine.