This is all very subjective, at least for me. It's kinda like asking me if I prefer wall art to have a landscape or portrait orientation.

I used to really dislike mass market paperbacks, but certain books seem to really work with that format. That dislike probably came from seeing so mass markets with terrible covers while growing up. If I really enjoy a book or it's something I'm almost certain to enjoy, I prefer to get the hardcover assuming it has the same cover as the paperback. For my favorite books, I have multiple editions and I typically get the newer ones first, then seek out the original covers later just to have them.

I haven't read the text of your post due to spoilers, but this is on my TBR next month. It's been collecting dust on my shelf practically since the book was released. I can't wait to read it!

I don't re-read anything. Maybe if I've put a book down for a few weeks or months, I might re-read a page or two, but never for just one day!