I'm trying the same (to get a 3DO and SWC). I don't know which kind of ports the 3DO-controlers have, maybe a joystick from another system is compatible (like sega genesis an atari controlers are...).
I think the 3DO is a unique animal in this respect. Genesis controllers "fit" into the 3DO but they don't actually do anything. There *was* an SNES adapter that let you use Nintendo peripherals, but good luck finding one (or a reason to want one).
There is, however, an absolutely wonderful 3DO-specificc flight stick from CH Products. In terms of form factor it was exactly the same as their PC Flightstick Pro... but it had the 3DO buttons and was integrated into control schemes for SWC and WC3. Great, great product -- search for one if you're serious about Wing Commander on the 3DO.
I don't think it ever really took off on the Mac (if at all really). I'm sorry but even today I just don't think there are enough Mac users out there to really get a fan base going.
Pretty much no one outside of Bungie was developing original games for the Macintosh in the mid-1990s... and Origin was no exception. Super Wing Commander was a port... but it was probably more succesful than you're imagining (as it was followed by ports of Wing Commander III and IV).
Gaming on the Mac in 2009 is a different animal. Since everyone is now part of the same Intel architecture family, any AAA title (...how few remain...) is now almost always PC and Mac compatible right out of the box. I need to order a copy of Sims 3 for my Macbook...
Anybody know if the 3DO WC3 was a direct port from PC?
It was not! Wing Commander 3 3DO is my favorite console port ever -- because they rebuilt the gameplay from the bottom up with a focus on action rather than precisely (and slowly) emulating the PC version (which is what the PSX and Mac ports did). All the missions are completely different in the 3DO one and the engine is a bit faster paced (and less graphically intensive -- it feels like a blend of WC3 and WC2).