Cheers!

First off all 3 manuevers you mentioned are MUCH easier with an AFT CG- have you moved the CG back as you got used to the airplane?

Secondly, you need as much movement as possible on all flying surfaces. Set-up dual rates so you can have your normal settings for regular flying then increase the movement- 9Use expo. to make your servos less sensitive around the center of the stick- and start purty high with these moves--) If you do not have a computer TX with these features, get one-

The Knife edge is all about having enough rudder "throw" to sustain flight using the engine and rudder only- just do 1/4 roll and input rudder until the plane can sustain the same altitude... Coupling might need to be worked out (Plane wants to roll out either way from that pos.) Push the CG back a little, get your rudder to move as much as possible- and give it a shot!

The flat-spin is also a maneuver that is easier when a bit tail heavy- (Even lower fuel level will make a difference-CG) I will let a 3D expert explain the actual maneuver since I am inconsistent when flatness is concerned!

The prop-hang or "Hover" takes ALOT of power, alot of movement on EVERY surface of the aircraft, and also needs a rearward CG... Just pull up and start practicing!