Trolling motor / and battery advice wanted

New to fishing, new to boating.
Just joined a rod/gun club with a small quarry lake used mostly for trout,
some bass. The lake has about 4-5 miles of shoreline. I bought a small semi
v hull row boat, and also want to purchase a small electric trolling motor
for it. Boat will either be carrying myself and fiance (combined 300 lb), or
myself and friend (380 lb combined) We may also, at times, use the
boat/motor on larger lakes as well.
How large of a trolling motor (thrust) should we be getting for normal use.
50 lb approx ?
What should I be looking for in a battery, any recommendations ?

Dave Henrie