C#.net/profile URL/

Question

hi,

i  m on a networking which includes blogging and internal mail like system...(passing text mesage to tables)..

now m facing two probs:

M using C#.net and MYsql in 3.5 frame work:

1. Now i created a 1 database, and insert  blogging details in one table and messge details in another table and user details in users's table..

any problem in storing details in one database? in future?

2. Or creating seperate databases for users ,blogs,messages...okk or gud

3.now am storing users images in one table and Videos,ADVS in server as sugggsted by one C#-corner memebr..it works cool....

but if my client want to change server any probs?

4.presently m using session and query string to view profile details: and my url is like

www.IAMSREEKANTH.com?profileid=123456 and username in session:

but , how can i code my, URL like: www.IAMSREEKANTH.COMm/username

pls help me??