I've been to Pismo twice this year. Whoops weren't too bad at the drags. No comp hill during the summer, well if there is, I couldn't find it.
The 1500 acre's that's available you can see in 30 mins, it's pretty small. It's great for bikes and farm equipment (Rhino's, Rangers, RZR's), not really big enough for a high power rail, it's too small and busy to really open it up. V-Dub's would be good.
I never had a problem with rust, I never stayed the night since we stayed at the hotels. I stayed away from the water and the main roadway along the water line. There is a highway away from the water against the hills, you can ride that to get to the dunes. Quads were washed real good when we got home and I dont see a spec of rust anywhere. There are a few coin washes in town where you can give everything a good wash.
It's hard to find a good flowing line in the dunes since the wind only blows in from the ocean, all of the steep faces are on one side. Dropoff's are scary and can be hard to see during certain times of the day. I recommend just taking an easy put around to get used to it before hitting 4th and 5th gear.
I will be back a few more times this summer for sure, maybe camp out for a few nights if I can make it work with the S-10, sand gets real soft 5 ft above the high tide line. 4 wheel drive is a must if you want to camp without the worry of the tide coming in.
Good luck if you head out, I will most likely post in "Other Riding Spots" if I make any trips out there. Maybe we could meet up and get a few rides in.