Questions on Mother 3 game mechanics

What's up guys. I have a few rather technical gameplay-related questions that I have been wondering about:

• As far as I know, PP and IQ try to be in a certain ratio with other. Does this mean Lucas's PP gains on levels will go up if he wears the Good Kid's Shirt? If he stops wearing it, will his PP gains slow down until the ratio normalises? Likewise, will he gain IQ more often if he wears the Awesome Crown?

• What determines what levelups you get? Is it predetermined, random or does it vary, but hover around certain benchmarks?

• At what point are you able to run over enemies in the overworld? Is it dependent on level, offensive stats or something else?

• Regarding comboing, how tight are the windows for hitting beats? It doesn't seem to be frame-perfect, but how much leeway do you actually have? Does it vary with slower or harder rhythms (like the looong breaks in Lord Passion's theme)?

• Furthermore, you're free to place the first hit whenever and only the following beats have to fit with the rhythm. But if you place the first beat just a few frames before the second beat has to happen, will you have to follow up immediately, or does the game give you leeway until the next beat? How big is this window, if it exists?

Hoping any dataminers or combo gurus can help me out with these. Cheers!