Tha's my opinion:
ffa-pvp (faction flagged players):
they should not be able to team with non-flagged players. To do so, he should unflag first, or the whole team should be flagged.
Flagged players should be able to use the teleport tickets, with the teleport timer doubled.
Flagged players should always consider they can be ganked without reason, because, showing a faction alignment to the opposite faction, is already a reason itself.
GvG-pvp (GvG regions):
this case should have a political behavior, just any player going in that region knows that can be the possibility to meet other people that eventually want to gank you. It's a strictly personal choice how to act in this cases. In any case, I don't think it can be considered 'unfair'. If you want to dig in that regions, you have to go there well guarded if you don't want troubles. Resources are needed by everyone, and it will be normal for a faction try to get them at the expense of the other faction. I'm always speaking of 'game mechanics' and *never* by personal considerations.
OP-pvp (Outposts flag):
Make the flag-unflag instant at the border and you will solve all the portal camping issues. Yes, with that rule you need to make different strategies, but to avoid exploits, just make the border of the OP area 'enough' far from the middle of OP (where there will be the real war).
Other pvp related questions:
aggro-dragging: in my opinion, it should be considered a 'legal strategy' only in case of OP war. I never did it, but i never considered it so badly. If there is a way to drag animals, then do it (if you are skilled enough to do it successfully). Animals will not differentiate from you and the enemies, so it's just another thing to take care when thinking of strategies.
Outside of OP wars, aggro-dragging should always been considered harrassment.
About the 'player banning' and 'guild banning', i think the 'guild banning' should be removed, leaving only the 'player banning'. In that case, if a people is not enough experienced (or was just too tired) to do the correct choice, it will be a good lesson for the next time.
That's all for now, or at least, for what I remember
EDIT: yes, the OP-flag should instantly cancel the faction flag, when you choose something other than 'neutral'