The 32 meg dram will allow you to play all the games for the super nes (super famicom) with the exception of Tales of Phantasia (which is 48 megs) and those games with special copy protection. My site does not specifically state this, but hopefully you were able to see that it doesn't matter which system you use (sram or dram) to play games. What matters is how much memory each system gives you access to. For the super nes, the sram system only has adaptors up to 16 meg. For the dram system, the max memory is 32 megs. The sram system is a little easier to use since the memory relies on batteries to preserve game data. The dram on the other hand requires the power of the system to store a game in memory, so you must always have the i/o plugged into the cartridge slot in order to load and play a game.
In response to your second question about the mega drive, the 32 meg dram will allow you to play all games made for the mega drive/genesis.
And lastly, there's the question about transferring game data to the i/o. Well, you can either use a mgd2 main unit to send data to the i/o. Or you can send data with a pc using the special pc link. I prefer the mgd2 main unit as it is definitely more portable than a pc. If you have any other questions about the mgd2, feel free to email me. Hope this info helps :-)