I've been asked by my job to write a iPhone app for an existing system for managing worktasks. This system is proprietary and costs money, so in order to login you need to be a customer. Now, I've got two questions about the legality of licensing iPhone apps with this system:

1. My company would like to be able to sell the app for profit, but not as a one-time payment, but as a added subscription-fee to the already existing one. Is it legal for us (according with the terms of distributing an iPhone app on the Apple App Store) to do this? That way we'll just add another field to the users-database saying weather or not iPhone is enabled for them, and distribute the app as a free app on App Store.

2. If the previous question is not legal, we'd like to just create a free app and distribute it as part of the existing system. In other words, no extra fee for using the iPhone app for the users, but still free distribution trough App Store.

Due to our company not being american or having an office in the U.S. at all enterprice account is not an option. Please let me know if there is anything wrong with any of the above approaches.