If your tablet were a 7 inch tablet, I would say to try switching firmware to http://techknow.freeforums.org/
uberoid-wm8650-1-3-0-hybrid-honeycombmod-v6-3-final-t801.html (remove space to get actual link)
However, I do not know if your 5inch tablet will work. There is ONE 5 inch tablet listed, I can't say if that is yours. You should post and ask on that site to see which firmware you should try.
If you do not need a microSD then you need a MiniSD.
Android market likes to ignore what you type and show you all sorts of pointless crap. Hopefully you have the real android market instead of the chinese one.