Good advice here. I've got an 846, which is essentially the same machine and like it a lot. Tip on the floor chain rails; NH wants a ton of money for replacements. I made my own out of some channel for just a few bucks and a little extra time.
Going to take a bit of time to get used to, you'll need to get a feel for making an even roll by weaving back and forth across the windrow a bit.
It's a good machine.