Gold Related Bans?

I have been wandering around the forums for a while now... I am rather curious about all these bans which seem to come up from trading items on the AH for gold. From what I recall in Vanilla Wow gold is rather hard to come by and getting enough gold to get mounts can be difficult. I see post after post where players transfer gold from toon to toon and get banned for it. I have friends here which I play with online and I would assume that if they needed a few gold that I am fine to trade it if I have it. Its one of the things I remember most from vanilla, that being the team work on most things. So two questions I guess...
I assume its not against the terms to trade gold to friends or loan them gold for things... but is this bannable? and how best should this be done so one is not banned? ( Id assume the same goes for things like crafted gear, potions, bags and else...)
What is the best way to farm gold for mounts?
I assume its not against the terms to trade gold to friends or loan them gold for things... but is this bannable? and how best should this be done so one is not banned? ( Id assume the same goes for things like crafted gear, potions, bags and else...)
What is the best way to farm gold for mounts?