Hi and welcome! Some personal advice, if you came to the Amiga for its games, get an Amiga 1200, add a harddrive, a copy of WHDLoad, an indivision and perhaps an accelerator board. You'll be able to play 99,5% of all games and can always upgrade to PPC to get to the remaining 0,5%
If you are interested in obscure operating systems, you are spoiled for choice on this platform.. Personally I would stick with the same machine and install AmigaOS3.9. Again you can later upgrade to PPC and run OS4.1 classic. But there are quite some alternatives, too. I hope you are ready to get confused and dive into it. The outcome is probably going to be good!
As for the Commodore64, look into the awesome Chameleon64 expansion. It turns your machine into the ultimate 8-bit machine.
