There is absolutely nothing wrong with the hand quilting! Do not take it out! Repeat! Do not take it out! I don't know what the stray threads are. Others suggest that they are tails you meant to bury later. If the quilt were mine, I would snip them off and forget them. And if I wanted to finish it with machine quilting, I would do that and put an explanation on the label. My labels nearly always give lots of information about the quilt. froggyintexas