Can I make iPhone apps with these specs?

I have Xcode version 3.1.3 and OS X version 10.5.8.

What is the minimum iOS version for iPhone apps that Apple will accept into the App Store and can I develop for it without spending any more money (i.e. with what I've currently got or via free upgrade)?

Can I develop a universal app for iPad with these specs as well?

What version of the SDK do I need so that the app runs on the latest iOS versions as well as the oldest acceptable versions (my current one seems to have deployment options up to iOS 3.0)?

Thanks for any help, I used to develop apps prolifically but have been out of the game for over a year and things seem to h开发者_运维知识库ave changed a fair bit.

Xcode 4 is a freely available for all members of the iOS and Mac Developer Programs. Xcode 4 can also be bought trough the App Store for 3.99 euro. Xcode 3 is freely available.

Only 'iPhone Developer Program' members can run applications on their device or submit applications to the App Stores. Joining the program costs 99 dollar. Otherwise you can only run applications on the iPhone Simulator and distribute applications through Cydia.

Compatibility:
What iOs version apps are accepted in App Store

Note:
You can actually distribute applications without paying 99 dollar, but only to Jailbroken (Cydia).