Good questions Amanda!
You would generally shove a lot tighter facing a raise compared to open-shoving. At 20bb, you wouldn't normally have an open-shove range, but at around 15bb you could jam wider than you would if someone had raised before you. So for example, at 15bb on the button, you can definitely open-shove A2o, whereas if the cutoff raised and you had 15 or 20bb, it would usually be much too loose to shove this hand. (ATo might be the bottom of your range.)
That's a cool idea to think in terms of: Villain raises 30% so I'll shove 15%, etc. But for me at least, that's not how I normally think about it because the profitability of your shove also depends on other factors like his calling range, state of tournament, and other active players.
E.g. if he opens 30% and calls 5% then usually you can shove ATC. If he opens 30% and calls 30% then you would only shove hands you wanted action with which might be 10-15% depending on effective stack, other players, and state of tourney. My advice is to play around with ICMizer a lot, get used to the results, and then begin actively quizzing yourself. Remember that you don't need to memorize perfectly and just want to make sure that you're playing pretty good ranges for the situation and making better decisions than your opponents.
Also, if you're ever not sure what to shove over a raise: Most pocket pairs, most suited aces, and all suited broadway hands. You'll never go too wrong this way
