All instruction sets are documented in English and it’s more esoteric so the tutorial scene in any non-English language is less developed, so that requires even more English skill than memorizing a couple of keywords in a mainstream language.
Dynamic yes, objecting to 24h. Many places keep the same dynamic address for months or years
Maybe yours does, but that’s not universal in the slightest
They know which IP address belongs to which customer at the time and anybody can download a torrent of some copyrighted content and see which IP addresses are down or uploading it at any given moment. No need to inspect RAM, no need for DO to monitor traffic. They (the copyright holders) will send a cease and desist through DO already, and could change to send a lawsuit instead.
Don’t give it internet access during setup.
For proper desktop Linux in that price range a used surface is a choice. It’ll be bigger and less battery life than an android tablet and I don’t know what the fan situation is in the generations in that price range now.
Another option is go with an Android tablet that has LineageOS support. You get fullish access to the system, but the system is still Android, so depends on what you want if that works for you.