1. No. But you will probably destroy the bearings hammering them apart so be prepared to replace them.
2. Keep turning, with mine the insert always used to start coming out, then stop and the pedal would eventually come out of the insert. A soak in penetrating oil wont hurt too if you haven't already.
3. Not sure I am following your description here, is your left arm on the right and vice-versa? If so, it is usually fine IF the pedals are good and tight, but as soon as a pedal starts coming loose STOP riding it, it will strip out very fast once there is any looseness.
4. Why is there no number four?
G.