Congratulations and Welcome to the Jayco Owners Forums !
Feel free to share a picture as I don't remember what your RV looks like.
I would suggest that the first thing to check would be the roof top and all of the dicor sealed areas on the roof top to make sure that there are no leaks and will not be any leaks. The roof should be checked imo twice a year at least. Leaks are a big issue with time and can ruin an otherwise excellent and pristine RV.
Depending on the tire make, they may be ok for a few years to come. There are a lot of debates and discussions on the subject here in the forums, however just as an example Michelin recommends annual inspections after 5 years and replacement even if no issues are found at 10 years. You cannot go wrong though changing them sooner, other than the cost.
If the RV hasn't been serviced recently and\or has high mileage, I would consider doing a complete maintenance service. Engine Oil change, transmission fluid change, rear axle fluid change, check\replace belts and hoses, filters, brakes, batteries, etc. On the other hand, these may be in good shape if your friend kept up with everything, but it would still be a good thing to check everything. You can likely find a Ford service manual that lists the frequency of how often to change the fluids, however the charts are of most value when you know when the fluids and other maintenance was last performed. ~CA