don't bother jump-starting the battery, for you will kill the otherwise good alternator by having it to work extra hard attempting to recharge the dead battery.
Borrow/buy a cheap replacement from elsewhere and swap the battery if I were in your position.
Also: personally, I don't dig the drigas thingy for most 87octane gasoline are pretty much E10 already, and will absorb some water/moisture in your old gas.
I'd add a bottle of techron in the gas tank before topping up with fresh gas, just in case that the old/stale gas might varnish up the injector orifice(pintle area) quickly.
Lastly, because it's located in so-cal area, assuming that relative humidity is low or consistently low to begin with and the vehicle is left in a cool/dry environment, gas in the tank should not be all that bad...so simply topping it up with fresh gas should be fine.
Q.