IMO here's how to preserve what ya got as long as possible. I live in the heart of rust country (we literally cheese brined our roads....so you gotta protect).
First its all about cancer prevention:
- Water isn't the enemy, so long as its got a place to drain. Keep drain holes in doors and rockers free of crap.
- Wash off any corrosive stuff immediately! (tar, oils, concrete, sap, any petroliate like gas or lighter fluid)
- Coat your blind surfaces with cavity wax to prevent rusting from the unpainted sides, especially important for old or modified vehicles which have holes and equipment in non-factory locations and may not be weathersealed.
Then its about treatment:
- If its got full paint coverage and can be waxed, a clean vehicle should get a complete rub on rub off waxing at each season (3-4x a year in year round climates). This protects the good paint from moisture getting under it, UV, and adhesion of icky stuff.
- In between waxings, when the vehicle gets a light wash or rained on, a spray detailer helps keep things looking good and extends the coverage life of the wax. Not needed for rust, but helps keep the paint healthy but allows for normal use and contact with the environment from daily life. It also helps prevent constant over waxing.
- Rock chips need to be filled ASAP. Buy a spot sander (pen/brush with an abrasive eraser tip) and scuff the chipped area, then dab in some touchup. Its like a cut on your skin...open wounds can get infection!
Patina is a different discussion IMO. Preserving patina depends on the state of decay, and what kind of paint is aging. I've seen plenty of guys lay 4-5 coats of satin clear right over a patina'd ride, and it looks fine for a while. However unless all the rust has been nuetralized, it will begin to eventually age through the clear again.
I also saw your paint feels rough; before you consider painting or anything like that, consider having a professional paint correction and see if something like clay bar or micro abrasive buffing could save what you have.