Trial account questions

All of the guides recommend testing your machine's muscle with trial accounts.

The RAF program works through trial accounts.

My understanding is that trial accounts have a level cap (20?), they cannot trade with people or get mail, and I guess they start out azeroth only?

The trial account section of the official site gives you a spot to download and start on your way, since I already have a main install is there a simpler way to start an unlinked trial account?

I am seriously considering starting 1-3 trial accounts to start multi-boxing with my main account, maybe 4 if I get crazy. The 2nd, 3rd and fourth trial accounts I assume are trivial, since they're spawned by RAF. It's the first one I am asking about because I don't want to link it to my main account.

When you say that trial accounts can't trade, is it that they can't open the window at all or can they put an item up for the enchant window? Reason I ask is runspeed enchant is a cheap investment that saves a lot of time at low levels before things like ghost wolf. My clothie alts all love their runspeed sandals, threaded tux pants and spelldam mining pick that they share.

Lots of people do shammies, I will likely too as my maiden attempt. If trials are limited to Azeroth, can I only do these guys once I've bought battlechests or gamecards to upgrade to real accounts?

When activating a trial account, a gamecard is instant but doesn't activate TBC, a credit card works but can have 72 hour delay unless you call billing, I'm assuming a battlechest activation takes effect immediately?

Though I don't care much about the zhevra mount, I'm guessing the first and third activation method above get instant mounts. Are they available to all chars on the referring account, a la the pets for the collector's edition?

Can a trial account buy things off the AH? (editsnip, did some more googling and I guess the answer is no, as channels, mailboxes, player to player trades, and the AH are not available to trials. I assume that's all to combat goldsellers, I see also max gold accum of 10).

Since shammies are draenai only, thus TBC only, do multiboxers stay in the draenai area through the L15 or so (great quest density out there) or just bolt at 10? Last 2 draenai I leveled to any degree were L18-20 before leaving the island.