You can use either duel rates or expo. I use duel rates on elevator and ailerons. I leave rudder on one rate. Whether you use duel rates or expo is your personal preference, but make sure you use one or the other on elevator since that control surface is the one most likely to get you into trouble. Before executing certain 3D maneuvers I switch to high rates. Then I switch back to low for normal flying. Some people don't like the switching, hence they use expo.

Also, there is a range of throw on the elevator between normal rates and 3D rates where planes can get squirly. That range is usually between about 25 and 35 deg. So try to stay out of that range. Either fly on normal rates or full 3D rates.

As for mixing, caps are well known for their pitching to belly on knife edge. So you will probably have to mix some up elevator with your rudder to eliminitate this tendency.

Greg