I would also recommend a book--"Enter the Kettlebell" by Pavel. It explains the basic moves as well as safety. I also bought "Kettlebells for Dummies". Both are in line with the RKC.
I havent bought any DVDs, but I have seen videos on the Internet or clips in tv shows where some of the moves are unsafe.
As for the weight, I would start with what you have. You can always go out and buy heavier ones. I started with a 10 pounder at the gym and now use anything from 15-35 depending on the move. With some moves, it takes very little time to move up.
Live the life you've imagined! - Thoreau