I believe my front brake came set up on the left, but that's how I like it.
The bike will handle hills better than anything, really. Loads of power and gear range, incredibly smooth shifting.
4" tire perks: makes the ride smoother, increased traction available at correct tire PSI, increased float on soft terrain.
3" tire perks: faster rolling in stock configuration, still a very smooth ride.
That being said, if you want the most out of plus/fat tires, you need to run em tubeless. I would never go back to running tubes in my fat tires after having made the switch.