Linux+php+remote MS SQL

Hi Everyone, I have spent a few hours searching on the internet, but still can not get the information I need. So I turn to you for help. I will be doing a web site which has a lot of data from a remote mssql server. The scripts will be in php and run on Linux. As requirements, the mssql will stay at the client's internal network, and linux server will be right here with me. For your information, we are considering using broad band connection for the web server although this has not been finalized. The web site will initially have 3000 clients, and the db will be updated on daily basis. For me, this is challenge because this is the first time for me to use remote db server, first time to use mssql server and first time to use combination of open source and MS products. Forgive me if I don't ask proper questions. The followings are my questions: 1. Will this combination cause a lot of problems? Will it be stable enough? 2. Because the db server is not connected to the internet, I am not sure what options I have in terms of connection to the db. Would some one point me a direction or tutorial about this? 3. Will remote access slow down the application a lot? 3. PHP has functions for mssql. Does any one know how those compare with ODBC? I would appreciate if you could share your experience with me or give me your opinion on the above issues. Thank you very much in advance. Ruth