Dude, I just use a shield, and I rarely get shot. Yes, you have to rotate if someone shoots you from the side...
No, carrying a shield does not make it so arrows never hit you...
If you have 3 or less shield skill, they can still shoot your feet and you have to lower the shield when they release their arrow to block it.
Or...You must have a bullseye on your ass.
Also, read my guide if a shield isn't working for you.