Can someone explain to me how the saving works in D3?? I've had to re-clear dungeons a few times just because I thought it would be ok to leave game when im back in town and halfway through a quest. Or say I restart my diablo halfway through a quest, and i join a pub game, then my initial progress is lost is it..? So confused!

Here's a party question -

1) if I'm in a party, the monsters get harder. Does that mean the exp gained increases also?

2) If answer to 1 is yes, then if my party member is not in the same map as me, do i get increased exp?