An easy answer to both questions.
Norton 360 is not available for the Mac, and will not install on OS X.
You would have to go with another product, and that gives you time to consider whether the resources needed for any virus protection software, and the minor possibility of it actually protecting your Mac from any active threat: on the Mac, there are very few legitimate threats. Anyway, you should consider whether the effort is worth the money. Most Mac users would answer "no" to that.
Now, if you are going to boot to Windows on your Mac - that's a totally different idea, and you should go with the same methods for protection that you would use on any Windows computer.
The Mac, and OS X - eh, not so necessary, IMHO....
But, the various antivurus companies do line up for Mac user's money .... So, they would like you to think there are threats coming
