Yes, you may develop applications for either Windows or Moblin. Please have a look at the following document for a good start: http://appdeveloper.intel.com/en-us/article/how-to-develop-application
Definitely... You can develop application only for Windows. It's working fine.
For window, need to take care of lib files only. (SDK).
You may submit windows entries without using the SDK so long as your entry is open source.
Can you submit a windows app without the appID bit and can you use the form file to designe the app
By appID do you mean GUID? If so, then yes you can, if the application is open source and you are not using the SDK.