Welcome to TBN! Congratulations on your new place. You've found a great forum to ask questions like yours. :thumbsup:
With 12 acres to keep up, I'd sure be looking at a bigger tractor than your friend's, no matter what you plan to do in the log run. Used is fine, and you should be able to find good 25 - 35 hp prospects in your area, newer than that MT180. Mowing that much property can get old real fast with a small machine. You also want something comfortable enough that your wife will be willing to help with the mowing from time to time, and maybe do some other chores with it.
Also, once you have livestock (I'm bettin' it'll be sooner rather than later once you're moved in), you'll be happy to have more tractor. You'll also want enough hp and frame size (especially enough weight) to handle at least a 5' box blade and a 6' rear scraper blade, for maintaining your driveway, cutting in trails, doing light landscaping, etc.
But before committing on anything, I suggest you spend lots of time on TBN reading posts on choice of tractor size. There are many threads on the subject, and the search function works well. It's not just a hp issue, as frame size and total weight is equally important to consider. Plan on kicking the tires of quite a few, and don't be afraid to watch a few opportunities go by before taking the plunge. BTW, a good rule of thumb is to figure out what size tractor you need to handle everything you're ever likely to do with it, then buy the next size up. :laughing: