Portals for alts: This one not explicitly in the ToU, but it does follow the same kind of idea as enchanting. This is probably OK. I wouldn't worry about it unless a GM says it's not OK. No one has ever been banned for that (at least going by the Account Issues forums, which I've watched since launch.)
Sending large amounts of gold between accounts: This is allowed. Theoretically to any amount, although people have been banned (and then unbanned) in some cases from false positives. I personally have traded up to 800g between my main & mage alt account, never had an issue. If you do get a ban on this, then just appeal.
TradeDispenser: Allowed. Viper has noted that using tradeDispenser won't get you banned. However botting (to avoid afk) will.
viewtopic.php?f=6&t=23552&hilit=tradeDispenser#p162525Any bot that would automatically make you jump or actually craft water & food would be a reason for a ban. TradeDispenser does not do either of these. It does automatically accept trades and put stuff in the trade box of course, and also automatically can periodically advertise.
Caveat: It is difficult for GMs to tell the difference between an automation tool, and a player hiding most of their UI, watching netflix in another window, and occasionally just jumping & making water for their trade toon. I suspect people have been banned unfairly this way, but there's no way to prove it either way. People who were banned who actually USED bots would of course use this kind of excuse in an appeal. Be aware that ANYTHING that causes your computer to take an action that you didn't personally direct is considered botting (like sticking a penny to keep the space bar pressed.)
TradeDispenser Multi-boxing: Almost certainly NOT allowed. You are not allowed to have an toon parked at the auction house (e.g. scanning auctions) while playing on another one. This would be similar; interacting with the world on two toons at the same time, possibly making money in the process. Even if you don't make any money by doing it, i'd stay away from doing that.