Nope it all just worked, it really surprised me honestly. I expected to need to do some weird tethering to a raspi or something to make it work but I didn’t need any of that. (Well, I had issues because it turned out lightning borked my router, but that was a different issue entirely.)
Many guides will suggest setting up separate partitions for a bunch of different Linux directories. It’s not strictly necessary to make things work properly. You can totally do it all on one partition (in addition to your windows one I mean). If you want to try something more fancy then keep a separate home partition, but honestly don’t worry about it much unless a guide or installer is suggesting it.
Nah. One big Linux partition isnt a bad thing and is a lot easier to grasp when starting out. (Though for dual boot you’ll need the windows partition somewhere still)
Backups are the main thing. Maybe a list of useful Windows software you have installed, just in case you accidentally break your install and can’t boot in to check what you had installed.
Make Windows recovery media and a windows install disk if you don’t have one. Just in case you need to go back and reinstall it can help avoid trying to do that without a working machine.
Test with a live usb first too. That way you can at least boot into the live Usb if things fail. And you will already have it prepared.
I think you could mount your windows partition as read only if that’s a concern. I don’t expect any Linux distros to mess with anything though unless you’re reckless about running install scripts.
Linux guides vary between “here’s a hack to just make it work” all the way to “here’s a perfect Torvalds-Approved perfect bomb proof 100page configuration guide”. Make sure you know what you’re looking for first and don’t get too caught up on making everything perfect. Focus on keeping good backups so you can restart from scratch if you ever need to. You’ll probably end up trying a few Linux distros over the next few years anyway.