does it cost to submit an app to the app store?

You have to pay a fee to Apple to become a developer, so in that sense, yes it costs in order to submit an app to the App Store.

You will find more information here. There is a forum for developers as well.

https://developer.apple.com/programs/ios/

https://discussions.apple.com/community/developer_forums

You will have to pay. You cannot submit an App to the App Store unless you are an Apple developer.