As to the first one -- yeah, i've always thought my PT kills counted as GV kills; havent noticed them falling short, but havent done a detailed analysis. As far as I know, the only MA kills that dont show on score are from Ship and Land guns.
Stats page shows all kills and deaths with kill credit going to a player; this includes proxies but does not include deaths or captures that occur without another AH player getting credit. For example, if you run out of gas and auger in the middle of nowhere, no enemy gets credit for the kill and your death wont be on the stats.
Scores only show kills you get with damage credited to you (i.e. if you ping once and a drone pops, you get score credit; if he pops without your guns touching at least once, it doesnt show up on score page). However, score deaths include ALL your deaths and captures whether another player got credit or not.
Could this be why some kills you got in PTs arent showing up for you -- were they augers without your guns touching?? Only thing I can think of.
