Congratulations on your new buggy!
I think that if you were looking for something to work out of, and drive around the acreage doing chores. The mule is an excellent choice. With responsible driving, and good maintenance, you'll get many good years out of it.
If it's 4wd, don't drive around in 4wd. That's ONLY for when there's soft ground. Those expensive tiny little parts in the front drive just won't take the abuse, over time.
There's plenty of accessories out there, depending on where you look, and what you want for it. Some accessories turn out to be extremely helpful, while others that I thought would really make a difference, turned out to be a disappointment. The best add ons are those you make yourself.
Here's a picture of mine. Those side boards are without a doubt, the best accessory I've added.