As far as stuck knots, I would say that make sure you are using the proper knot for the application you are using it for. Not trying to be condescending or anything, I use to have the problem but after a few knot books, and some online reading you can learn more knots then you probably would ever need to know in your life.
As far as the ends go, for easy and cheap I'd say wrap it which electrical tape and just cut off the tip to give and nice clean end. Knife will do, but a heated blade would work best. If you use the blow torch, the frayed ends will melt in and create a lumpy mess at the end.