Best Practices/Helpful pointer for Web App with Struts/Hibernate

[Anush Malhotra]

Hi All,
First post. I am returning to web development after a period of 2 1/2 years. I have the requirements for a project which are as follows.
The application is for a Bank, the number of users concurrently hitting the DB is 3000 and it would be using Struts/Hibernate/MDB/SQL Server 2005 with an App server
I want to ask you the following questions. Would appreciate any points/URL's from your end

1. What is the ideal connection pool size that I should specify in the configuration file
2. Any Best practices for implementing connection pools
3. If I do want to have a transaction that involves MDB and DB updates, how should I link them up
4. Any other best practices/Do's and Don�ts for Struts/Hibernate/MDB/SQL Server 2005 would also help.

Cheers.