Please recommend me the best J2EE design pattern

Hello
I decided to rewrite my J2EE application.
This application will be installed on Websphere App Server 5.

My application should return XML's (as String) from remote requests, probably by webservice/es .

There should be 9 kinds of requests.

Which design do you recommend me to use ?

Please suggest a detailed suggestion, as like
1) how many webservices should i use ? 9 services or 1 ?
2) how many EJB's should I use ? What should they do ?
3) which EJB to use (Session ...facade... etc... )
4) should i use JMS & MQ ?
5) How can I avoid memory leaks ?
6) Can you give me a known design name ?
7) etc....

Thanks !