1) Does the usb stick with my wav files have to be MODX formatted to import them, or can they be read MAC formatted?

Needs to be FAT formatted. Most sticks come this way when you buy them. Sandisk and other manufacturers who like to put extra partitions (for utilities) on the sticks will generally not work and require a complete wipe of partitions which would mean using a computer to do this. Formatting on MODX isn't going to wipe partitions. Other users have had issues formatting on a Mac - although I'm sure there's some way to get it to work. You could "dd" over an image with master boot record and all. That's technical. Hopefully there's an "app" or builtin that works OK. I've seen lots of users with issues, though.

The best way is to "discover" a USB stick that comes pre-formatted ready to go and make sure to get enough of them to set you for "life". Using these sticks only for firmware upgrades or data storage/transfer with your MODX.

2) Would it be best to use “Init Normal AWM2” instrument for this type of sample playback? (key pressed=‘on’, key released=‘off’)

Best is subjective. That would be a fine place to start. Although drum keys can be used for this as well. Drum keys can be set to either play one-shot all the way through or not (stop when you lift the key).

3) So, I import these wav files, create the performance with the new waveforms as three separate parts, then save the performance. Will any part of this process erase my user preset bank (over 100+) ? Also, will the new waveforms be saved permanently with the performance where the usb stick is not needed for reference? IOW, do I need to save the waveforms first in my user bank before creating the performance?

When you say "three separate parts" above - I don't know if you mean that each sample is going to go in its own Part (as in MODX's use of the word "Part" ). If so, just be aware you should put all 3 samples into a single Part unless there's a compelling reason to use Parts. Off-hand, I can't think of one considering you're using fingers and not MIDI to trigger these.

The User Bank won't be erased unless you tell it do so. Loading individual samples doesn't erase the User Bank.

The 3 samples will be placed into internal Waveform memory. After loading there is no need to keep the USB stick attached.

Your steps would be to start with something (say Init Normal (Drum) or Init Normal (AWM2) ), load up your samples from within this Performance you're editing (go to the drum key or element and load samples) then [STORE] this Performance which creates a new User Performance. That's how I would do this.

Thanks for the info guys! I was assuming that each waveform would be three separate parts of the performance with set key note ranges. I guess I still have to dig in a bit more on this as Bill suggested!
So, if the three waveforms are put in one part of the performance would they be added as separate elements with separate note assignment? If that’s correct I could see the efficiency in doing it that way.

Thanks Bill!

Yes, just use a single Part. Using a Drum Part is probably the easiest way to do this. The AWM2 system (non-drum) has a set of cases where it is a "best fit". Regardless of what would be "best fit" - it may be a good start to use a single Drum Part to map your samples as a "training wheel" approach. There are less steps to get this going and (opinion) it's easier to visualize.

If you wanted to pitch stretch samples across many keys (say map just a few samples across all keys) - then you'd have to use AWM2 (non-drum). This isn't the case here.