If you're going north I'd advise taking 128 out to the coast and then 1 up to Leggett rather than 101. The final section (once 1 leaves the coast) is amazing.
Yup.
If you're on sport bikes, and it's your first trip, I will recommend you keep the daily mileage down a bit. By the third day, you might be happy you didn't bite off a huge chunk.
Highway 36 is great, but it's a long, long highway ride to Red Bluff. If you intend to ride it, I would suggest you blast up the highway on Friday afternoon and get a fresh start on 36 in the morning after some rest. Then maybe find your way down the coast or 101 a bit after checking-off 36 and make Sunday shorter than Saturday.
Something like this:
Google Map
It's not too ambitious. It gets you out of the back yard. It will give you plenty of time every day to stop and take in the sights and still hit some epic roads. It will also keep you in the area of some fantastic riding which you can add to, or subtract from as you go. Without knowing whether you're a mile-eater or enjoy shorter more intense riding or even smelling the flowers, this will only commit you to one long, boring stretch of highway and it's out of the way at the end of the first day.
I will agree that Hwy 1 from Ft. Bragg to Leggit is awesome, and it is better riding south to north, so maybe if you have time you make a loop by coming down 101 to Willits then over to Ft. Bragg on Saturday, and start Sunday by riding back up to Leggit on 1 and then back home. Make plans for both then call an audible when you're there, depending on how you feel.