The volume seems pretty good considering that you have those compound movements in there which count for a bit more than isolation exercises.
The variation is probably optional, you're still in the beginner stages you'll pack on muscle just brushing up against the weights. Since one of your goals is improving pull-ups I think you may be better served doing pullups more often. Maybe swap out dumbbell hammer curls on pull day 2 for more pullups?
It varies from person to person and how you have been training, but generally it's around two years I believe. But in training terms it means that you can recover faster and pack on a lot more muscle than someone who is more advanced. In my first year I gained about 20lbs, second year 10lbs and third year 5lbs. I would consider myself moving into intermediate level now