I locate the recommended Maintenance for your rig
Look in your owners manual, they will have all the details and times
If you have never done these items Id at the least assume they were never done and go after the yearly items
Oil, Filter, Air Filter, Grease Links, Generator fluids
Check & top off Transmission, Brake, Coolant, Stabilizers
I use this for Motorcraft Specs
https://www.fcsdchemicalsandlubricants.com/
For my 2019 FR3 I keep an excel spreadsheet.
Check those that are not yet required for change (top off if needed)
Replace those per Service Time
Oil Change 5W20 (7 Quarts)
Oil Filter FL820S
Air Filter
Transmission Fluid XT-10-QLVC
Power Steering XT-10-QLVC
Coolant VC-3DIL-B
Rear Axle XY-75W140-QL
Brake Fluid DOT 5.1
Lubricate Front End Chasis Grease XG-1-E-1
LUCAS LUC10013 Fuel Treatment (1 Pint)
Stabilizer Hydraulic Oil Motocraft Trans Fluid MERCONŽ V
Side Lubricated Gear Track CRC - 3045 Power
Slide Cleaned & Lubricated Seals Thetford 32778
Wiper Blade Replacement Wiper Technologies WT1-28
Gen Quaker State SAE30 (2 Quarts)
Gen Cummins Onan 149-2341-01 Fuel Filter
Gen Cummins Onan 140-3116 Air Filter
Gen Cummins Onan 122-0836 Oil Filter
As for your Grease Points, yes I do mine once a year
As for brakes, Id take them in to a qualified shop 1st, have them do it ask if you can watch, this will give you an idea if you can do it yourself next time