If you are really going to level with him all the way (I'm little sceptic that at some point other one will have more time or something like that), maybe you should go ele so that:
A) it's easier for you to heal when you actually have mana and +heal to do so.
B) you are not after same gear so that he can have melee drops and you can use cloths etc.
C) you should still both be dps but you will just check his hp and give some healing if needed.
If you are going to do so then you must let him pull mob and take agro so that you can heal if needed. Also with that team you can just take 3 random dps for low instances since you can heal and he can tank with shield. Just leave some gear @ bank for that.
Still, only thing is that you have to play specc that you want to play. If you prefer melee just go with melee. Leveling together gives mobs no chance since you will be cutting right through them in no time = less healing needed.