This is the sort of situation where I would recommend taking a step back, finding a good book that covers the topic, and read it cover to cover. At least for me, taking time outs like this to learn something in an academic manner has paid big dividends over the years.
I would call BS on this. Yes, git is pervarsive, but if you learn alternative tool (mercurial, perforce, even svn), you will find that learning git (at least for being productive on team that uses git) is straightforward.
Also, haven't seen a company that actually tried during interviews ti figure out if you know how to use git or not.
I'd suggest that anytime you go into a situation where you're not sure if you'll mess something up, just make a full copy of your project on your local file system. Then try stuff out on the copy. Then you can try branching and such without the fear of messing anything up. Once you get it, you can repeat the process over and over to make sure you know it. You have to be able to fail without fear of wasting days of your time.