I'm brand new to Unity. All of my programmer friends are C# enterprise app gurus, and have said if you're going to learn coding (which I am), buy reshaper immediately. After I paid for it, I realized it doesn't work on a mac. So I bought parallels, just so I could get used to using reshaper. I really like what it does (for what little I've actually made use of it for).

I haven't tried installing Unity on the PC portion of parallels. If I did this, would reshaper then insert itself into monodevelop? Is there a switch in monodevelop that allows it to access reshaper features? Or does it not work like that? I'm sorry if this is a dumb question, I just started working through Unity tutorials a few weeks ago. I'm very new to this.

Resharper is an add-on for Visual Studio; it does not work in MonoDevelop. It sounds to me like using Parallels to use Visual Studio just to use Resharper is a lot of silly hoop-jumping. Resharper is nice, but contrary to what your "enterprise app guru" friends assert, I don't think it's that essential.

If I were you I'd get a refund and go back to your usual, native-platform workflow.

Resharper is fantastic if you're running Visual Studio on Windows.  Otherwise not so much.

If you want something nicer to use than MonoDevelop, try JetBrains' other product, Rider, it should run on Windows, Mac, or Linux.  It's got most of the same refactoring tools and other bells and whistles that ReSharper adds.

P.S. if you're a student or still have a .edu email address, you can usually get a student license to the whole JetBrains suite, which has all kinds of goodies.