RE: aerial rocket launching
If you must, stick with a rocket ignited on an air dropped R/C airplane, like the X-1. That is entirely reasonable and allowed by the AMA. There just isn't the velocity and energy involved with a rocket assisted model. It'd be a little more interesting than usual, with performance about the same as blipping an engine's throttle to maximum for 2 seconds (these engines don't burn very long) and shutting it off. But, I know why you'd want to do the rockets... it's cheaper, but not necessarily safer. I'd hope you are an advanced modeler before you attempt this.
I like the idea of a the X-1 rocket, because in the case that the motor does fire on the model, the X-1 will stick to the B-29, the B-29 is too massive to get a push from the rocket motor, and all is safe. Those little rocket motors will have the chance of firing at people from a radio glitch, and they won't be locked onto the model.
Keep the hobby innocent.