Insulation, Radiant and Vapor Barriers - Insulating old cabin in the Sierras

I have a 75 year old cabin located at 7000 feet in the sierra Nevada mountains here in California. The only insulation is in the attic which we added when we replaced the roof last year.
I'd like advice on insulating the walls and the floor, please.
The walls are full dimension 2x4 with 3/4 inch pine panels on the exterior I would prefer not to remove. The interior is also 3/4 inch knotty pine panels. Can I add some R-15 batts and blue foam board under the pine or just the batts?
The floor is 1 inch T & G doug fir supported by 2x6 joists every 24 inches. The joists are supported by pier and posts above bare ground. Clearance is 18 to 48 inches. Again, can I put some batts under there and add foam or just the batts.
Summer cooling is not a problem. Winter heat is by wood stove and direct vent propane heater both exiting through the walls. It is COLD in the winter!
Thanks,
Steve

I would recommend using just the batts and forget about the foam boards. You want ground cover over the dirt floor in the crawl space. This is to avoid any evaporation of moisture in the ground during the winter. Because it uses the heat inside the cabin to create the evaporation.