Learning the basic ins-and-outs of OpenGL ES on the iPhone took me about 3 weeks. I post some of my observations on the subject here. The source code to my Molecules iPhone application, which uses OpenGL ES, is available here. Maybe you'll be able to find something useful in that example. However, there's nothing in there that deals with textures, which you'll probably need for your game. Bill Dudney has posted source code for a Wavefront OBJ modeler on the iPhone that may help in that regard. For a good text on OpenGL ES, I'd recommend "Mobile 3D Graphics: with OpenGL ES and M3G".
When it comes to Cocoa development in general, it will take you a little while to get up to speed. For me, it was about 6 months before I felt comfortable with it, although that was in the more complex Mac desktop environment. I post some resources for learning Cocoa here, although that's by no means an exhaustive list.
I agree with diciu, this is a bit much for someone just starting out on the platform. I'd find a simpler application or series of targeted applications (that you may never even release) to help you learn the core concepts before you leap into 3-D game design.