I have a 2015 version along with the newer 865R. They share the same engine along with the 1000 series tractors. Your first hints:
1. The oil filter is a pain to reach and cap wrenches are iffy. My go-to is the Motivx Tools Small Adjustable Oil Filter Wrench for Removing 2.5" - 3.25" Diameter Spin-On Oil Filters from Amazon. Just get it and not frustrate yourself. You put the wrench on first and then slip your 3/8 socket wrench in. Also, if you don't use JD filters, be careful on the compatables. Some are about a 1/2 inch longer which makes them too long to get in/out. The Mobile 1 M1-108A is an example of the correct size.
2. Get the tech service manual. There are usually CDs on eBay. Just looked at it for $35. Snatch one up as they come and go.
3. Buy all your filters in bulk. Buy a Gates (32G4588) Drive Belt to keep on hand, or better yet, get 2 if you see wear. There are threads on properly preparing the belt and installation hints.
4. The fuel filter is a pain to change. Least painful is removing the assembly so you can get at it. The tech manual describes it well. I relocated mine to the right rail.
5. Consider street or lug tires that fit on essentially trailer rims. Lots of options. Better performance on most everything I do. There's a sticky in that forum on it.
6. If you hate having to haul loads uphill, consider a turbo. I put one on my 855D and never looked back. There's a review on it as well. I'm likely going to put one on my 865R now that it's out of warranty.
Bottom line, just use the search function on 855D and there's a pile of great stuff on it.