AFAIK, Visual Studio isn't and never has been available to run on OS X, so you'd have to either run it under Boot Camp or a VM app, such as Parallels Desktop (I'm a Parallels user, so that's what I usually reommend).

In November 2016, we introduced Visual Studio for Mac, the newest member of the Visual Studio family. Visual Studio for Mac is a developer environment optimized for building mobile and cloud apps with Xamarin.

Is 256GB enough? Just barely. I've a lean, mean 512GB SSD and I use just a portion of that with a full 377GB free (after I finally consolidated my entire iTunes library onto an external drive). And I run XP under Parallels. SO you could get by with 256GB. And, if you wish to upgrade later, OWC has a 480GB storage card that you can install - for $580 (compare that to the cost of the Apple 512GB upgrade - I think that you come out cheaper with Apple).

Yes, you could get by with 256GB - keeping in mind that you can always upgrade to a larger capacity card later on.

Microsoft Visual Studio 2012 For Mac

Clinton