Fire seasons tend to run long. Don't count on set beginning and ending dates, and don't plan on leaving early; you won't be invited back again. Ever.

There are some copilot positions that come up in the BAE-146's and RJ-85's. You may be quite some time upgrading.

There are air attack positions that open up in turbo commanders and similar aircraft.

The largest element of the tanker fleet are SEATs (single engine air tankers); nearly all Air Tractor 802's. You'll need a very solid conventional gear (tailwheel) background, 802 experience, mountain experience, and low altitude working experience. Of all the fire positions, those will the the hardest to get, but they do pay well.

Sometimes.