I'm not sure how helpful this will be, but generally speaking, I tend to only buy books that I've already read and enjoyed enough to want a copy of my own, with exceptions being sequels and authors I know I like. (I also usually buy used, when I do.) Depending where you are, you probably have a few (legal) ways to do it this way, too.
If you want to read something specific:
- Libraries. If you're interested in a new release or very popular work, you might have to wait a while for your turn, but otherwise, it should be relatively easy to get a lot of things, either in person, through library apps, or through interlibrary loans.
- Kindle Unlimited. I don't personally have experience with this one, as I'm not a big Amazon fan, but seems like a good way to stretch your book allowance/limit regret at picking a dud.
If you just want to try a variety of things, risk-free, to see what you might like:
- Little free libraries. Heavily dependent on whatever others donate, but if you're lucky enough to have one near you, you might find something worth trying.
- Public domain. Obviously, limited to very old stuff, but maybe you'll find something interesting.
- Assuming you're reading fiction, some publishers, fiction magazines, and authors offer free things (full e-books, excerpts, short fiction, etc) on their sites. Short stories can be a great way to get a feel for many authors quickly.
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As to your other question: I find paperbacks way more comfortable to hold one-handed; no need to choose between eating and reading! They're also usually smaller and lighter than hardcovers, so you can 1) fit more in less space, and 2) carry more at once when you move or rearrange.
The book is great (imo), but know going in that the movie is a very loose adaptation. They share the same premise and basic plot, but many of the events don't carry over between versions.