Is there an easy way to
1) make a network private to the public and then
2)let subscribers from the main blog ask to join the sub site blogs using their profile data from the main blog
3) and without having to fill out registration forms or enter passwords and log in information for each sub site blog that they want to become a member of
4) and let the admin of the sub blogs receive a notification email that a request is pending to be a subscriber
5)still let published custom posts show in network search results.