Multiboxing advices

[Teremius]

Hello guys I'm new to the multiboxing thing and I'm so hyped to try it out on Classic.
First I'd like to ask if there's any private server where I can experiment and get things in place before Classic comes out.
Then I would ask your opinion about what class is the easiest to start, I want to farm dungeons (trash) and so gold, I want to try what I never achieved in WoW and that is to be among the richest players in my realm. I already enjoyed every aspect of the game but the economy is what is left for me to explore.
I will play alliance and I can't decide between Mage and Warlock. Once 60 I want to farm dungeons as much as I can, what would be the best choice in your opinion? I will use 3 accounts.
Thanks everyone.

[Ughmahedhurtz]

Some important information in this post. Hope that helps.