These don't make any sense, like the script is distorted or something.
1) Where the mattress came from? Julia didn't die on the mattress!
2) Julia didn't make any deal with the cenobites how could she come back?
3) Why had she come back in almost full flesh, but Frank in first part came first as almost a skeleton, was it a budget issue?
1. Yes, she did. After the cenobites ripped Frank apart, Kirsty ran into the bed room and found Julia lying on the mattress, holding the box with her face ripped off by hooks, and then wrestled the box from her dead hands to send Pinhead back to Hell. I know the common question is how did she end up there after dying downstairs from Frank's attack. Well, apparently she didn't die there and somehow made it up stairs.
2. Frank didn't make a deal with the cenobites either, and he came back. The first movie established that spilling blood where someone is killed by the cenobites can resurrect them. Since Julia bled all over that mattress, it could be used to resurrect her too. But in addition to that, she DID make a deal, but with Leviathan. She said it herself, he was the god who sent her back.
3. It could have been a budget issue, not wanting to go through the various stages of rebuilding, but it's also possible that Julia got more blood than Frank did, since she had a whole person slicing himself all over and Frank only got a little hand blood from Larry.
Ffs dude, did you even watch this film or the first????
1) Yes she did, you see here at end of first movie laying on bed with box in hand.
2) She made deal with Leviathan, nothing to do with Cenobites. Frank in first movie escaped. Julie was set free.
3) See 2.