I don't think any wireless controllers are working with jb 4.2.1 and there seems to be interference from wifi using bt headsets. Don't know about keyboards, don't have one to try, wouldn't be surprised if they have problems too.
I was using WiimoteController until the 4.2 update. It no longer works. If you read the description on Google Play, they are trying to patch around the Jelly Bean Bug.
Until then, try a usb controller. The update added some support for them. My logitech dual action works with an adapter for usb to usb micro. Or is it mini. Native support, no app needed.
I think Gamestop has a usb controller with a mount for 7'' tablets. Might be top-heavy.