I think the sms mod is still required on the Genesis 3 before the Everdrive can play sms games on it.
its just a single wire to hook up to the cartridge port.
if you got lucky and got the VA1 version of the Gen3 then you can pretty much do everything with it, if it's a VA2 then you are more limited as Majesco sales cheeped out on the chip that runs the show, these are not made by Sega!
you can tell which version you have by looking though the cartridge port, if you see a large diamond shaped chip its a VA2