LTE/Long Range Dual Band Wifi Build Questions

Here's the list of everything of what I have:

  1. Dell Optiplex 755 (Running Windows 10)
  2. Sprint Mifi 8000 (USB Modem)
  3. 45dbi 4G LTE Mimo Antenna (2-meter cables)
  4. TP-Link Archer C7 AC1750 (V2 Router) (Running the latest Goldenorb)
  5. 2 Remo 15dbi Dual Band Wifi Antennas' (15ft long cables)
  6. 1 (Black Slimline-Type) Dish Satellite (Primary Wifi Antenna installed going one way.)
  7. 1 DirecTV Grey Satellite (Backup Wifi Antenna installed going the opposite way.)

Now here's my questions....

  1. How to connect the mifi via usb to the router after firmware install?
  2. How to find out what bands I'm currently using in which how can I set up band lock from the router? (B2, B4, B12, B25, B26, B41, and B66 is the closest Sprint and T-mobile towers near my home of what I've found via cellmapper but I think I can connect to atleast 5 of the 7 combined bands when the mifi is connected to the router).
  3. How to tune and set up the router to correspond with both dual band antennas for the purpose of Long Range Wifi Internet?
  4. How to set up load balancing with all of the combined Internet sourced connections with failover?
  5. Besides the mifi, my other internet sourced connections is of course, Public Wifi..... But since I'm drawing all these opened connections, what's the best way to be safe and keep my privacy intact besides buying a VPN...?

*Disclaimer, I only returned to Openwrt for advice and help so no smart or rude comments please, I have ooma internet home phone, and my OTT/OTA all reliate on whatever home internet I have and I attend to get the most out of what I have build. Eventually, I want to make a YouTube video of my setup once everything is dailed in.