I think "hell" is your own worst nightmare. For Voldemort to be a weak suffering, helpless, miserable little heap that was probably the ugliest most horrific thing he could imagine. AS someone said before for MR. Power hungry being weak and helpless is the worst.

Also as far as the trace --all the illegal magic he performed was in the home of wizards so the trace wouldn't have shown the ministry who performed it. Remember when Dobby dropped the pudding Harry was blamed! In a muggle home who ELSE could have performed the magic but Harry!! Plus Volde was smart-- he knew how not to get caught in all his other criminal activities why not this!?