If your radio actually used all of that 10 amps, I'd be amazed. The same with the tablet. 2 amps for a tablet must be what they rate with a dead tablet battery trying to be charged and in use at the same time. I don't think you will have any issue tapping into the radio fuse.
Edit to add......use a fuse tap and try it. The worst that can happen is that the fuse blows and you can go with option 2.
[This message has been edited by IMSA GT (edited 08-10-2013).]