Works with Android and Windows 10 I've used it with.
Surprisingly, this model doesn't work with Apple except for some iMacs. Apple changed something and now doesn't support it.
Takes typical AA batteries.
Comes with batteries.
Light scratches on the back. The camera makes that one in the middle look worse than it is. Not deep enough to try to catch a fingernail on it.
The bottom-left few keys and a few on the right have a brownish line on them. The low-front picture shows the inside is quite clean of dust and things. The camera is five inches away.
Use it for a few days, if you don't like it bring it back.