Magic Using Follower question

Hey so I have been using Lydia as a companion, but as a Melee focused character I was thinking about trying a magic using follower. So my question is how do you handle them in regards to spells. Do they just have a preset magic list and that is all they can do or can you give them books and they will learn those spells? And what other noticeable differences are there in how you should handle them versus melee or ranged followers?