If visiting on a Saturday (beginning of November, for crowd reference), how much transit time can be expected between the entrance to Animal kingdom and the restaurant, if using their busses? (Don't want to miss out on too much park time!)

I'd say 45 minutes to be safe. That being said... The restaurants understand and don't generally keep you to a tight reservation time.

Is the lunch menu almost the same as dinner

30-45 minutes depending on wait time your bus. As an alternative, you can always take an Uber. You'll probably wait about 5 minutes for your driver ti arrive and then about 6 minutes travel time. Total cost will be less than $10.

The buses run about every 15 minutes from the animal kingdom park to the animal kingdom resorts. Sanaa is at the second animal kingdom resort stopped at. About 10 minutes from park to resort. Also note that the resort busses are at the furthest stop at animal kingdom park

30 to an hour should be enough time. They usually hold your reservation 15 mins after your reservation time.