1. Bind off normally in knit. It's easiest and it's probably not going to show at all.
2. If the tail is long enough that's fine (but don't pull too tightly), if not then get a new piece of yarn.
3. There are many ways to do this. Some people weave it under the purls, some weave it in like you were doing duplicate stitch. I usually do the latter.
4. I'd just use needle and thread. Make it secure, but don't pull too tightly.