Which Mesh Extenders and External Antennae for ORBI LBR20-1USNAS

I'd like to improve LTE cell reception for my Orbi LBR20 and also extend a mesh network across my drive and into a shop.

The Orbi router is in a window upstairs struggling to pull down US Cellular's LTE from a tower several miles away--through the trees and over the terrain. Line of sight is hopeless. While I'm not totally opposed to running a cable for a roof-mount outdoor antenna, I'd like to know if a pair of those 5-inch LTE antennae plugged into the router's connectors would help.

For extending the mesh, I'd like to position a satellite in a window at the opposite end of the house, 44 feet away to give coverage to an RV parked in the driveway and serve as a bridge to the shop (140' away). I can put a second satellite in the shop window to provide WiFi throughout that building.

Questions:

1. Which external LTE antennae work well with the LBR20?

2. Are 6E satellites back-ward compatible with the LBR20? I don't want to buy something that's going to be obsolete any time soon.