Don't know - I don't make a habit of counting them. As to the proportion of the player-base, it might be better to consider them as a proportion of the forum user-base (recognising that the vast majority of players have not registered on the forums).
Not when they register specifically to whine. If they count you need to considered everyone who didnt register because they didnt get ganked. Beyond that, I find it an odd statement again "If PvPers are so great, why are there so many angry posts about them online?"
Change 'PvPers' with 'black people' and see how far you get without reporting yourself.