My Advice dude, keep the Guppies and Platys there really good fish to start off with, and shoot the rest off somewhere or sell them. Cause there not going to be happy in a 2ft tank, with some of the neighbours they have, and your not going to be happy when they die and your moneys down the drain and you just lost a pet. With so many fish in a new tank your going to be having all amount of water perameter problems such as amonia sp. Best thing to do, is do some reading ask alot of questions, and then deside what your going to do, we can give you advice on Cylcing periods, what fish go together, and signs of sickness Etc. Theres a big wide world of information on this hobby out there buddy, the learning is honeslty neverending, and you've just stepped into a very interesting learning experience, and a really neat and highly kept hobby at that.
Shae