Exchange Consultant

We are a Saas company and we are looking for an Exchange Consultant to help us integrate Microsoft Exchange Server calendaring with our software. We don't need to know how to hook into the Exchange APIs - we need assistance at a higher level. These are a few of the questions we'd like you to help us figure out: How do we construct the best calendaring solution? What role should our third party software should be? A user? A room? Who we should authenticate as in our calendar client? What requirements do we place on our customer in terms of exchange configurations? What common security practices might make our use of the APIs challenging? Qualifications: You should have opinions regarding the above questions. Ideally, you should have experience with large scale (10,000+ users) exchange calendar integration. Ideally, you should have experience building 3rd party software applications that are aware of appointment accepts and declines and can schedule events on behalf of a user.