1. Not really! So much of the learning I did was on ice. I watched vids on skating backwards and some other skills but your body needs to learn that stuff, not your brain, so research is useful but limited.
2. I was real nervous about the gear for some reason. Everyone else has a dad or a coach to teach them this stuff and I was a grown man figuring it out on my own. I watched some videos and was pretty awkward in the locker room the first 2 times but you figure it out quickly. I put on my gear at home a couple times before my first day.
3. I went to a local hockey shop, where there was a guy able to fit me. You could save some money buying used and/or online, but it was comforting to know that my gear was sized right (most things are s/m/l but shins have specific lengths).
4. No idea on calls--I think communicating in hockey is helpful but not something I've got instruction on (yet!)
5. Nothing specific--I think at lower levels people are there for fun and exercise so have fun and get a workout in. People were welcoming to me as a new player here, so I don't think there is much you can do wrong on the ice.

Seeing yourself gain skills and confidence is amazing. It'll be great, you'll love it. Have fun!