I would like to know the implementation method of the following common functions which may not be limited to blog development.

1. I would like my users have their blog's URL like username.mydomain.com, how can I add their sub-domain after user activated their account? need active directory?

2. how do i manage user's blog entries and uploaded graphic, use code to create user's folder after user account activation (number of folder = number of user)? or store them as object in DB(seem more efficient but the DB must be very busy)? or use active directory(if I can add user account by ASP.net and window will generate their profile)?

I have no idea the common practice on user management like web hosting, weblog.. Thanks