If you are referring to the California Inmate Firefighters Program, they could be out in the forest for weeks at a time during the heaviest season.

You can call the chaplain or the unit team secretary and get a "humanitarian update"

Almost all in-person visitation is suspended until March 30, 2020. The inmate's movement, in many cases, is restricted so it is easy for them to enforce any type of quarantines necessary in the event that an inmate would contract Covid-19. 

Yes, you can call the facility and speak with the unit secretary, case manager or counselor.

Inmates in hurricane areas are transported days ahead of the storm making landfall. In my case, we were in a federal camp in Miami FL when a couple hurricanes hit Dade County. They loaded all the inmates onto buses (shackled) and driven to downtown Miami where the Federal Detention Center is. This is a tall structure in the middle of all the government buildings. It is more like a skyscraper for inmates which can and did withstand several major storms

The phone restrictions would be limited to the normal phone procedures - the lines get longer during these times so frequency and length are cut due to heavy demand. The only issue might be that if the inmates get moved to a safer location their commissary/phone account might not immediately move with them. They would still be able to call collect.