dragon tomb question
 

can i go back in dragon tomb once i go in?

Yeah, as long as you're in a party.

Yes you need to be in a party and be level 85+ then go to Uruga chief as far as I know.

As long as one person is inside the tomb, the map won't reset.

Even if your entire party is wiped out, it wont reset unless you all leave the map.
Meaning all you need to do is have everyone but one person respawn outside Tomb, come inside, and that last person can go.

It won't reset as long as you all go out the exit that is behind the dragon. If not, you need to disband the party then get back together for it to reset.