I don't believe there have been changes made with the recent expansion.
Just be aware that you will lose your appartment (clean it out before betraying naturally) and you will lose all master spells and every spell will be app1.
Further to that, what happens with my pp in the bank. Will I need to take it with me or will it transfer over to Qeynos? I'd hate to get ganked on Venekor carrying a lot of loot.
That I don't know, but I do believe you get access to a bank in Haven. I would say that your bank account is also cancelled, meaning that you have to clean it out too!