GW2 Account vault
If you put everything in your bank and delete your characters everything in your bank will remain. Keep in mind if your friend’s server is full you will have to wait for an opening.
Further reading:
http://wiki.guildwars2.com/wiki/World#Transferring
You can transfer at no cost by deleting all characters. You can place anything that is not soul-bound in your bank, and it will transfer with you. You can read more about transferring in the Wiki: http://wiki.guildwars2.com/wiki/World#Transferring
Good luck.
Just remember, that you won’t be able to transfer any soulbound gear (or rather, you will, but for obvious reasons it won’t be usable by any other chars anyway)
Remember, remember, 15th of November
Rustux: you don’t have to change to your friend’s server at all, unless you want to do WvW with them. PvE and sPVP can be done by anyone in the same party (if in the same region: NA, EU, or CN).
If you really want to change now (while you don’t mind deleting your character), then just make sure to unequip everything that is account or unbound (e.g. bigger storage bags). I’ve deleted more than a few toons and about once every fifth time, I forget something like that.