I can do some of these:
1) & 5) A porpoised landing is when pitch control on landing is incorrect. The aircraft might, for example, touch nosewheel first and then rebound into the air. The pilot pushes forwards to counter this and the aircraft descends again, contacting nosewheel first and bouncing again. This continues for a few cycles until either the pilot does the sensible thing and goes around to try again or the nosewheel collapses. If you visualise the motion, it is a bit like a porpoise or dolphin does on the surface of the water. An aircraft can do this in the air and is also due to poor pitch control.
2) A balked landing is one where you change your mind and go around. (Balk: to miss or omit intentionally)
3) I can't remember exactly, but I think I saw somewhere that aerobatic flight is beyond 60 degrees of bank and/or 30 degrees of pitch.
4) You need to check in the POH or the aircraft documents for your particular aircraft. It should be in the weight and balance section along with the examples that Cessna do for you. Don't take someone's idea that it is about 40.0 or whatever.