1. Paracord's never broken on me before. I've worn some down to the point where I had to replace them, but they've never broken on me. That's a big advantage over chains. If you're unfortunate sometimes a chain chucks can break without warning.
2.

I use this. It's easy to do, has never come apart on me, and makes a nice small knot that fits inside chucks very well.
3. Airport loop is the best for disassembling, but I don't like that typing method because I'm extremely picky about my cord length and getting the perfect length with an airport loop is extremely difficult. I also don't personally like having the knot in the middle.
4. 2 string is the way to go.