As for catching sunfish with 10 pound test line I have seen it done many times.
I personally use 6 pound test line.
Bass anglers while fishing for bass using heavier test line have caught their share of sunfish.
As for Snelling your hook I would not think it would matter either way on catching sunfish.
I have fished with anglers who use the Snelling method and have caught their fare share of nice sunnies.