what partitions do linux distros need to function ?
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.
is it bad idea to install linux on a single drive in its own partition ?
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)
what precautions should I take other than backing up my hard drive before doing dual boot ?
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.
How can I ensure my dual boot linux install won't touch my windows partition at all if I install dual boot linux ?
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.
Is there anything else I should be aware about ?
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.