An excellent site dedicated to crawling is...
http://www.rccrawler.com/forum/
not to take away from the good replies you getting from the people here but that site is all about crawling so it's a much more comprehensive resource for the questions you probably want to answer. As others were suggesting RTR would probably be a good thing to start with ... Losi nightcrawler isn't bad ... Rc4wd bully 2 is great... Knock off the axial XR-10 wish I love you and I think is probably one of the best rock crawlers ever made