I don't have much doubt there will be different levels in Hell. I can't see your average adulterer or liar being punished the same way as Adolf Hitler for example, who was responsible for the deaths of millions, apart from the massive destruction he caused, the tortures, the murders, endless cruelties and incessant lies he told as part of that work.
Personally I think the devil made an attempt to take over the earth using Hitler, but fell short that time.
It gives you some idea though of what the earth would be like if he did succeed - one big concentration camp from one end to the other, ruled over by pitiless tyrants.
As for heaven, Catholics believe the ultimate ecstasy will be to gaze upon the beatific vision. If we get to that point, we won't care what our heavenly status is, as we will be so wrapped up in beholding the essence of God.
There will be greater and lesser saints, depending on how faithfully we carried out our mission, but frankly I don't think we'll care much. If there is a regret, I think it might be looking back on our sins, and also what we didn't do that we should have done - sins of omission.
But I don't think we're going to care about our status in heaven, since our perception of the beatific vision will be so overwhelming. That's all that's going to matter in the end.