As far as preparation the most important thing is to keep at least the 8 precepts and be practicing meditation. I don't believe your expected to support yourself but I would recommend having saved money for visa runs if your in another country.
Doing various chores and cleaning is dana. Giving your time and energy to the monks, laity, and the Wat is dana. You really don't need much when at a Wat most of the requisites are provided for.
Everything is a learning process you are NOT expected to know all the customs. Training is all apart of being an anagarika and the preparatory period of becoming a monk. I would suggest you spend more time at a Wat to learn chanting.
Check out this video might help to answer more of your questions. http://www.youtube.com/watch?v=ittQd5zk ... plpp_video
I'm also looking to go to Thailand in April to ordain. I've spent two months in a Wat in California.