Mixture lean maybe a couple of times during the climb, and again when at cruise (just gradually for the RPM peak, then as per your SOPs - some schools try and help the engines last longer and teach to run slightly rich). Icing only a problem with visible moisture. I've flown a Warrior many times over the Rockies at 11,500 with no problems...enjoy the smooth ride! Oh another thing...expect the rate of climb to dwindle very quickly above 8000ish feet!