Hope you’re doing as well as can be during this pandemic!

I’m looking to do some interval training on my bike indoors and have some questions.  No bike shops are open near me so I can’t go in and talk with someone, and Saris hasn't responded.  I don’t bike that much but have the mountain bike I listed below.  I don’t feel the need to track my miles, power, etc…just want to do some riding at different speeds/time for 20 minutes of interval training.
  • Will the Fluid2 trainer work with my 2017 Giant Stance 1 mountain bike?  I have some specs that might be helpful:
    • Current rear tire (orig equip: Maxxis Ardent 27.5” x 2.25”
    • Current rim (orig equip: Giant CX-1 [ETRTO 584x23]
  • I’ve read that the training tire is recommended:
    • If I didn’t get one and kept current tire on, rough estimate range of miles would the tire last (trying to keep it simple)?
    • If I had to buy a training tire, which one would I need to get and would it fit my wheel (listed above)?
  • What benefit would the optional "external speed sensor” provide?  I don’t think it will enable adjusting the resistance, right?
  • Will resistance change with shifting gears on the bike?   Thanks for any help you could provide!