@dovid Hi! Thanks for the great questions!
Disc rotors are sold individually or as part of the brake set, not as part of the wheel, so you'd need to purchase those separately. Disc rotors are not very easy to switch between wheel sets, so it's probably going to be easiest for your project to have a set of disc rotors for each set of wheels and leave them attached. Your local REI Co-op Shop can order those parts for you.
Derailleurs and disc brake systems are very sensitive to changes in spacing- although most wheel hubs are manufactured to about the same dimensions, there will be small differences in the spacing of the disc rotor and cassette between different brands and models of hub that can cause rubbing of the disc rotor and poor shifting. It's not likely that you'll be able to switch these wheelsets with no adjustment required.
The really good news is that those adjustments are generally really easy to make, once you have a little practice. I recommend checking with your local REI Co-op shop about disc brake and derailleur workshops offered there. You can let the person offering the workshop know what your goals are and they can help answer specific questions during the class. With those under your belt, these little adjustments when switching your wheelsets will take no time at all!
Hope you found this helpful! Happy riding!