I haven't floated below pittsburg to hellers so cant help you there.
heard it is flat and upstream wind can be problems
Lower granit is a 2 or 2 1/2 hour float from the dam, you'll probably have no problem., Lower oregon hole on the oregon side a mile or two further is much nicer. The lower camp is an easier hump for gear hauling
I don't know where cat gulch is?? Below Kirkwood?? Kirkwood is at about mile 30, the lower part at kirkwood is nice plus has a toliet
salt and sturgeon rock (pine bar) upstream are also nice. Salt is on the oregon side and nice beach, sturgeon is on Idaho side and nice beach but both are hard to nab
we launch next thursday and jet back to the dam sunday from kirkwood.
It was a 100 today near boise and will no doubt be much hotter in HC
here's a pretty good map Boater's Guide
let me know if you have any more questions