I've just explained to Bactalan the purpose of different DB. Perhaps you have work around to achieve that easily.
Do you propose custom coding services or do you know someone that offers this kind of services?
Do you have site example, tutorial links for the ~#2
for #3 our goal is to create a community portal for customers and prospects. We would like to propose shared materials but also resources only available for customers. Perhaps there is a way into the profile fields to store this info and to personalize the code to make it possible...