I am wondering if the SEAT positions are filled by the Feds or by contractors and who hires for these postions?

3GreenKSNA is right on,
If you're looking for time in that world see if Aero-Union, Minden, Neptune have a parts plane ( some one to shuttle stuff around) you'll get exposure, time and build a network. Many of the big Helicopter companys do the same. From the outside these guys look crazy but the reality is the flying's very regimented and specific. Last summer was my first year as a smokejumper co-pilot, we fly a similar profile. It is fun, there are risks, and you either love or hate the lifesyle.
Cal Fire Air Attacks and Tankerpilots don't leave Cali much, they use vendors for the pilots so your not a State employee good contract, hard to get.
Find out were the Tankerbases are to start networking probably in the southwest or SoCal, Redding had some tankers the other day but this time of year most will be in winter maint or somewere near Texas.
CalFire's big aviation shop's in Sacramento at McClellen Airpark.

If no one is hireing and your loking for an intro to the life work as a temp on an engine, crew or helitack if you want to stay off the line a tankerbase hires temps and the retardent vendor usually hires temps to do the pumping. I was a tankerbase manager for 3 years while I worked on ratings and time, I hated leaving my helitack crew but it was time well spent with all the waiting I'd study and there was never a shortage of pilots to ask questions.
Good Luck