AFIK it's a "fork" of the tor-browser (which is a fork of Firefox) but instead of connecting to the tor network you connect to a VPN.
So you get all the in-browser tracking protection Firefox has (e.g. against fingerprinting) + the ones only the Tor browser has but without the drawbacks of the tor network and in turn without onion security.
Yes, but beware that many websites are broken when “resistFingerprinting” is enabled. That’s why that mode is not enabled by default or an opt-in option in Firefox’s settings UI.
I've ran into a couple ones that have some canvas-based features that break when resistFingerprinting is on. They get some visible noise added on top (which does indeed thwart fingerprinting, but also makes it harder / weirder to use those features).
I believe you can turn off the canvas-based meddling per-site. There's a small icon that appears on the left of the URL input box on affected sites that allows you to do this.
The Tor desktop browser is based on Firefox ESR (Extended Support Release), Mozilla’s LTS branch of Firefox that receives security fixes for 14 months. The Tor Android browser is based on Mozilla’s regular Firefox Android browser, updated every four weeks.
So you get all the in-browser tracking protection Firefox has (e.g. against fingerprinting) + the ones only the Tor browser has but without the drawbacks of the tor network and in turn without onion security.