Hard to know without seeing it or knowing age, abuse, etc. If you're not too sure maybe just retire it or find someone to inspect it who knows their stuff. Most wear is on the ends and some people just cut it off and use them in the gym if the rest of the rope has life.
Depends on what you mean but it is pretty common for a rope with alot of use to get some fuzz on it. I normally don't worry about it unless I can see the core or you fold the rope over and it doesn't give a nice firm rounded loop on it. All ropes are different good to see how it folds over when you first get it so you know what it should look like to compare to later.