It is indeed fuel leaking from the damaged wing. The F18 has whats called a "wet wing". Each wing will hold about 1000lbs of fuel. There are 4 internal fuselage tanks (5 if you count the Vent tank at the rear) Also the vertical stabs are fuel vent tanks as well, and may hold a few gallons of fuel.
As for Skydrol, the F18's I worked on never used skydrol (its pretty nasty stuff). MIL-5606 is pretty standard.
My experience with them is that they are pretty remarkable birds.
I have seen this type of damage before caused by the same circumstances and both aircraft made it home that time too.
Ask any F18 driver and he will tell you that this aircraft will get him home.
Great Aircraft..I kinda miss being around them.
cheers,
RTR