1. Might as well. There is a gully that you might cross before the upper ridge that i think has great avalanche potential. I say might because it depends on the route you take. If you stay on the ridge as best as possible, dangers will be minimized, but certainly not eliminated.
2. Depends on how comfy you are. the ridge can be nicely exposed at times, and sometimes steep enough that self arrest is not practical, depending on conditions. Not overly technical though, so if you are confident in your step i think a rope may be extra weight. Oh, about quest 1. If you are camping where i think you are (just below the ridge proper on the east side), there can be avy danger getting there, especially if you head right up the gully.
3. time, depends on how fast you are. given recent snow, plan on a long day.
4. i have no idea
5. Glissading the gulch might be nice, but keep in mind "avalanche" gulch. Decending the ridge might not be that bad, Ive decended the lower half and after you already have steps in this is very straightforward. Good luck
youve checked climbingmountshasta.com right?