I am using Unity3d (free) and want to publish to either iOS or Android.
If I buy either the iOS($400) or the Android($400) add-ons will I be able to use and publish games (for iPhone and Android) with Unity (free) ?
Any help is greatly appreciated.
Yes that is why there are two types of license for mobile. You can pay $400 for iOS and and release an iPhone game using that. Or you can buy Unity Pro AND iOS Pro for $1500 each costing a total of $3000 and release a game using the pro version.
Here are the options/what licenses you need to publish to iOS: