Hi Chris and welcome to the coolest computer discussion board on the net, discussing the coolest computer designed.
What he said is generally true. A A1200 will the most easily give you decent computing power with easy backward compatability if you want to play around with the old stuff, and "relative" ease of parts to upgrade it. AmigaKit, is a super store, from which to get your fix.
Of course, if you run into any problems, there are many here willing to answer your questions. You might be surprised at the speed at which people answer your inquires. :-D