The server transfer just moves you.
The faction change lets you pick the race and appearance.

Not sure on how long between each you need to wait.
It was a couple hours or less for transfers.
There's a 3 day lock out until you can re-transfer.




I would personally move to the new server, if I was sure my friends were going to be in game for an extended time.
Not much point, if they will quit again in 3 weeks when they go back to university or whatever.
Still, your existing realm sounds dead, so that means no economy to buy what you need etc.
So a move somewhere is probably a decent idea.




I would liquidate anything which can be sold, and is not useful to your team.
Don't go and get rid of your gear on the other toons, you might want them at some point.

Get all the gold you can manage onto one toon.
Pick the most geared of your toons.
Unless you have one with all achievements or something else as a consideration.

Server transfer (and faction if need be) this one toon.




You already have five accounts.
Presumably Classic + Burning Crusade + Wrath of the Lich King for each.

And you have one toon on the new server, with a decent amount of gold.

I would purchase four vanilla copies of warcraft.
The basic game, not battlechests.

Send yourself RAF links from two of the other accounts.
Do not send the link from the account with the transferred toon.

Use the existing toon, to "boost" your four new toons.
That is two toons on existing accounts, which did not server transfer.
These will be toons you are keeping beyond 60th.
And two toons on the "vanilla wow" RAF accounts.
The vanilla accounts can be Orcs or Dwarves, or something equally generic.

I would probably RAF boost, 2 (or 4) sets of toons to 60th.
Which then gets you one (or two) extra level 60, from granted levels on your existing (already upgraded) accounts.

Then repeat the process, but with the other two already upgraded accounts.
And the remaining two vanilla (disposable) RAF accounts.

You will end up with 3 or 6 toons, on BCDE at 60th.
And 1 toon on A, at 80th with a bit of gold etc.
The 80 can continue to boost the other toons.
Or you could transfer characters around.
Or even transfer others from the other server here too.




In the meantime, you can one-box with your friends on their server.