To clear the ears I and many others use the valsalva technique. This involves holding the nose and
gently blowing through it to equalise the pressure.
Yes, I have been airsick during flight training. Very hot and rough day on a PPL cross country. Another time during spin training for my instructor rating. Later as a pax in a C206. Very first time was my one and only experience in a glider. Haven't been in one since.
Re the ear popping. It shouldn't be happening too often. Make sure your ears are fine to fly before you get going. Do the above technique, there should be no difference in the rate at which they equalise. If there is, consider not flying. Make no mistake, otic barotrauma
hurts.