1) Yes, Job system
2) Why would you need it? You have the job system
3) Levelling up is not mutually exclusive to either of those, is it?
4) You control one character in a party of up to 6 AFAIK
5) With online play, it's a slightly more accurate simulation of real life RPGs. Each player controls one character in the team (meaning you'll have to play the role of your one character). You also get to play along with people who aren't necesarily in the same room (or country) as you.