TheBum
You don't have to have neg. pitch for a roll. If you going fast enough and start the roll once passed 90deg then reduce the throttle stick to half (ie hover setting) and keep the momentum it will do a full roll. It ain't pretty ill give it that but it can be done and i do it.

dtacmed
Not sure why you would want to do these maneuvers with out neg. pitch but the loop can be done well. Once again get good fwd speed and height, once passed the 90deg mark back the throttle off to half stick and your good to go. Be careful not to back the throttle stick off to much though. Let us know how you go it is a lot easier than you might think, once you have done it you'll be asking yourself why you hadn't done it earlier