mac mini for software development
I have dual core i5 macbook pro with 4GB memory. I am working on an iOS game in my free time. I am happy with build times and debugging performance.

On my system (running OSX Lion) I have around 200MB free memory while debugging on the simulator, around 300MB while not debugging. Debugging on the device consumes less memory than the simulator. I have iTunes and safari open which consumes a lot of memory too. So 2GB memory may be somewhat insufficient. You should have 4GB to be safe.

As for the native code question, Apple will almost definitely allow native code apps. They don't allow Flash. They don't allow Java. They don't allow just-in-time compiling of .NET/mono. They actively develop, advertise and enforce their SDK. They allow freely mixing C/C++/Objective-C in your code. They also allow script based games for example, Corona SDK uses Lua as scripting language, and there are many games developed with Corona SDK. You should have a look at such SDKs since they allow developing both in MS Windows and OSX. Also such SDKs allow you to develop cross platform apps, which means you can develop for iOS and android at the same time. However, you must have a mac and iOS developer account (99$/yr) to debug and publish for iOS (no such restrictions for android).