TSRA+ I think you are confusing the issue a little. Cancel SID/STAR means just that ( cancel it laterally and vertically) The controller should have said cleared 5000 unrestricted if that was what he intended (not cancel SID/STAR ). If they dont give you "unrestricted", then you should do as you did and comply with the 6500 restriction. If they say cancel sid/star they must issue another clearance (laterally aswell - as he did with you.." fly hdg...")
Almost Okay - imagine you are so heavy that you will reach the waypoint which has the at or below 7000 restriction at say exactly 7000 or maybe a little lower (ie you did not need to level off) it would make sense to just continue to fl200 as you have already complied with the 7000 or below restriction. The same applies if due to your aircrafts excess performance you will need to level off before reaching the waypoint at 7000. Btw in the example you gave, departure controller always says stop climb 7000 just to make sure you don't bust it. If that happens then you shouldn't climb above 7000 without further atc clearance (unless lost coms)