About Unity Pro IOS

I want to develop for iphone, what should I buy the 400$ license or the 1500+1500$ one? Whats the difference between these two apart from certain feature missing?
Can I use Unity free and Unity IOS to publish a commercial game??.

You can compare different licences of Unity in the store (Unity licences) and see the difference between basic and pro and see what features you need.

As for the publishing, you can publish commercial game with any licence (you can see that in the Unity FAQ)