[kyteflyer]

You might find that there is no single app which will do all that you want. Sadly, that is usually the case.

I read that thread you referred to (I had never heard the term Share Sheets and am still a bit mystified) and saw that Florence had referred you to a browser called iCab Mobile, which may go some way to assisting you in the matter of html to epub.

I've looked at a lot of readers over the years and havent yet seen any that do all you want. Bluefire might do much of it, so might Pocketbook REader, but neither will do everything.

[edit] just took another look at Bluefire REader, and its probably going to be as close as you'll get to what you want. You can authorise for Adobe DRM, and annotate, define, copy etc. There's also some syncing between devices. Dont know how it would go for PDF, as I don't use those. Its free though so you may as well try it out.