RE: Slow Roll
Step 1: You don't really have time to "learn" the slow roll on a model moving at 200 mph. Consider getting an inexpensive pattern(ish) plane to learn with. The slower airspeed will benefit you greatly and all pattern planes are very honest around the roll axis. The Great Planes Dirty Birdy ARF at $299 is very inexpensive to get into the air. No need to worry about retracts to learn this maneuver - go low budget - the model flies superbly and is an excellent rolling aircraft, even in a "dirty" configuration.
Step 2: Break the slow roll down into 2 segments. 1st segment is the transition from upright to inverted. think about taking about 2-3 seconds to roll from upright to the inverted position. Make sure that the model is absolutely level, or even very slightly nose up before you start your roll. As you approach the knife edge position, you'll want to feed in some "top rudder". That means if you're rolling to the right, the first knife edge position will require some "left" rudder to help keep the nose from dropping. Don't try to hold a knife edge.. the plane should continue to roll beyond the knife edge and for this reason, the amount of top rudder you'll need usually isn't much. As you continue past the knife edge position, you'll ease out of that rudder and start easing in some down elevator to keep the nose from falling. Once inverted, hold the plane there to allow yourself to make whatever small heading adjustments might be needed to get the plane back to straight and level inverted flight. Once the flight has been stabilized in the inverted position, simply roll out at a comfortable roll rate. Remember, you're concentrating on learning the transition from upright to inverted, not the other way around yet.
Step 3: once you can make a slow transition from upright to inverted while maintaining your straight and level heading, then you can start working on the transition from inverted to upright. This will be like step 2, except that the "top rudder" will be opposite of what it was when you rolled into the inverted position. Once you can transition from inverted to upright while maintaining heading, then you are ready to put both segments together without the pause in the inverted position.
Get this maneuver down with that pattern plane (or any plane that rolls reasonably true around the roll axis) and then the only thing you'll have to adjust to is the mach 3 speed of the jet. Once you have the maneuver down, I think you'll find it easier to hold heading at 200mph than it is at 85 mph.
One thing for sure - that slow roll (properly executed down on the deck with the jet) will be well worth whatever amount of work you'll have to put into learning the finer aspects of the slow roll!!!