My issue with premium is that it doesn't fix so much of the other shit that revanced fixes for me on the mobile app (I don't want shorts, community posts, I want my dislike button etc) that I'd be using revanced anyway. And at that point I can just also block ads. If piracy gets you a better experience than that of paying customers, then you have an issue with your product.
The best you've got right now is using it as an unofficial web app. Go to the site and under the menu add it to your Homescreen. The rest will come with time.
No, upvotes used to be boosts but they switched them recently and haven't updated the reputation to reflect that (probably because the servers were on fire)
It's mainly a feature of other ActivityPub platforms (it's the equivalent of a retweet on mastodon) so I'm sure it's partially there for cross-compatability between them.
It's more of a "this was deleted, we suggest you do it too". Ultimately it's open source so anyone can modify this stuff to their liking and individual instances can choose to go along with a delete suggestion or not.
You should theoretically also be able to tag something as deleted but only actually delete it after a week (for example). This would comply with regular delete suggestions and keep things synchronized as one would expect but would give a bit of time to defend against an instance going rogue and self destructing.
Or someone checks through the activity of obscure posts and happens to find someone they know liking something they dislike or disagree with. It's not me, but my suggestion stands!
Some apps just have a floating button like the "return to top" button to add a new comment. Works especially well on mobile, can imagine it feeling quite janky on desktop.