I pay for mine, not sure how it differs from the free version but you can turn logging off, or if you have logging on you can specific how long to store logs and what jurisdiction to keep them in (I keep mine for a few months in Switzerland). You of course have to place some trust in NextDNS the company that they are actually doing what they claim to do as far as respecting user privacy but I trust them more than Google and Cloudflare, which is what I was using previously.
That’s part of the fun. Sometimes you get someone else’s fuel points too. It’s kind of like gambling whenever you fuel up. Over the long term it probably evens out, or at least I feel like I get a fuel discount pretty often with it so I don’t worry about it. Worse case I’m helping someone else save a few bucks, it doesn’t feel like a problem.
There’s only a subset of addons available normally, this method lets you make any addons you want available on Android. This is what I’m referring to: https://www.androidpolice.com/install-add-on-extension-mozilla-firefox-android/
You can get any extensions you want on Android with Firefox Beta (or Nightly) by creating a custom collection at addons.mozilla.org
No, they effectively do the same thing so you can just set your router to use NextDNS and you’re good.