You should be okay with the default values of the KeyStep when used with the Minitaur. You obviously can't and don't want to use the Arturia MIDI Control Center software, so you're going to be stuck with the defaults. But that should still allow you to perform those basic functions out of the box. You won't be able to adjust the CG/Gate values, and probably won't need to. As for the firmware, you'll probably have the latest as it hasn't been updated since last August, and then only once. Only the truly new (and limited) black KeySteps will definitely have the latest firmware, but there's no way that I know of to tell whether or not a white one has been on the shelf for a month, or for a year.

Yes, there are tons of features and tweaks available in the MIDI Control Center software, and only a number of limited functions are available on the KeyStep itself through key combinations. But you should have access to what you need to create patterns, play them back, adjust the tempo and connect to the Minitaur.

I could be wrong, but I don't think the Minitaur responds to velocity or aftertouch. Perhaps it's accessible through the Minitaur software (which you are not using), I don't recall as I don't use it much. But if it does, I don't think you're going to find a way to access it or control it on the surface of the Minitaur. You might find you have different results and more functions using a MIDI cable as opposed to CV/Gate cables.