Those are some hard questions to answer. A 10" jon boat with 2 people aboard is going to be pushing a lot of water. Its just the nature of the beast.
Personally I do not like Motor Guide due to too many bad experiences with them. If it were me, I would get the biggest 12V Minnkota I could afford. You never know when that extra push will be needed, especially if a strong wind comes up. As for batteries, there again bigger is better because the higher amps they are rated, the longer they will last. But you have to consider weight too. Hopefully someone with a similar rig can jump in here and help you better.
Fair Winds and Following Seas
Bill H. PTC USN Ret
Chesapeake, Va