Create a new thread and post those questions. I can give a little bit of an insight. There is somebody here in QN that has a complete product for the iPad and the iPhone. He can give you more details too. However, scrap your idea of C# or C++ in iOS.
Don't scrap the idea of C++ in iOS. iOS is just a regular unix. Take a look at my QuantLib/Lua app on iphone:
This program is a combination of C++/Objective-C/Lua and it runs beautifully