1. Using the toon on the opposing side to get honorable kills. Only for achievements, I don't play in battlegrounds. Things like getting Halaa tokens or earning kills for City Defender.
Win trading applies only to Arenas so I reckon this will be absolutely fine. You're open to attack from other members of the opposing faction in world PvP so it's not a risk-free gain.

It's a little grey though, so I'd check with a GM to be absolutely certain.

2. Using the toon on the opposing side to get /who info on people for world PvP
Absolutely fine. There's a handy reference to this in a post about Angwe somewhere else on these forums:



3. Using the toon on the opposing side to sell faction-specific items to myself (such as the argent tournament pets from the opposion faction).
Absolutely fine. There's been lots of discussion about using the neutral AH for this sort of trade and the blues have always said it's completely legitimate. I don't have a reference immediately to hand, but it won't be hard to find when you look.