"3. Is a project more/less likely to succeed if the many (Dev/Deploy) roles on a project are actually filled by different people as recommended in SCEA?
J2EE Product Provider
Application Component Provider
Enterprise Bean Developer
Web Component Developer
Application Client Developer
Application Administrator "
In real world scenario, its very rare that EACH of the above mentioned jobs are done by different people. Generally, all the developement (EJB's, Clients, etc) , assembling and sometimes even deploying can be done by the Developer.
Administration can be done by a different person as opposed to the developer doing it as administration needs more in-depth understanding ...