Development of a Simple i-phone app

Features to iphone app built from scratch would include: 1.) A similar menu layout as the beauty tips app I sent you 2.) A message board for users to post and interact with each other (I would supply a hosted domain and site for that probably using Simple Machines Forum) With the ability for users to sign up to this message board from their phone/app 3.) I was also wondering how much it would be to add a gps function for users to make their location known if they chose to?