Skip the rom sites; they're limited goods wrapped up in advertising. Go hunt down a Torrent from whichever service you prefer (torrentreactor.net or similar) - people have seeded torrents that contain the entire SNES collection. Similar torrents exist for other platforms.
re `six-button gaming` - try the Logitech Rumblepad 2. It's a PS2-style USB controller. The buttons are somewhat programmable via a mode switch. The controller is automatically recognized by Win2k+ and works seamlessly with MAME and ZSNES - probably works great on other emulator packages, too.