The yellow is the spawning channel. Below that, the green is the boat launch. North of the boat launch is all spawning channel, no fishing (in that backwater off the main stem.) The orange is all open to fishing.
As far as parking goes, it gets busy. Be there before sunrise. Last weekend, sunrise was 730, and I was there at 6, and still the third vehicle. The main place to park is at Hayward and Keystone, right beside silvermere lake. Just show up at 7 in the morning, youll see all the cars.
If you want to fish the back channels, you dont need waders, but your boots will be filled with water. The main stem is easily accessed without waders. Then again, actually getting to the river, many people walk up Hayward to the Ruskin Picnic area and scoot down and into the river. Sometimes the Hydro people will let you, but I have heard of one or two people working there not letting people through.