John Deere 310C New owner lots of questions

I just purchased a 1991 JD 310C 4x4 extend-a-hoe with 7000 hours and i have no idea what i am doing! I own a kubota BX and a 8N but this is way different than anything i have ever owned. It runs great and everything seems to work as it should but there is no service history other than it was purchased by the previous owner around 2000 and used to build a house then landscaping snow plowing random property tasks since then. I want to service it and am looking for advice. I ordered oil, air, fuel, and hydraulic filters from JD, there are a couple hoses that could be replaced. main questions 1. What oils should i use? For the engine oil it looks like rotella 15-40 will do. Should i use synthetic since it will be parked outside in the winter -20C and used for plowing my road, or stick with the conventional oil? 2. Should i drain the hydraulic fluid (20 gallons?) or just replace the filter if the fluid looks good? 3. Should i service the front axle, and if so how do i do it and what fluid (type and amount) for it? 4. Any advice on things i should check over on it, and how to? 5. Are the transmission, rear end, and hydraulics all connected and one fluid used? 6. Are there any sources of information or guides that you recommend? Anything else i should do/look at right away? It wont fit in my shop so i want to get it all sorted before it gets cold Thank you very much