Tomcat/apache subdomain and SEO issues

I plotted to make rewrite/subdomain clearly before the job/yellowpages modules applied, I just thought I make it clear by the way, but since I was puzzled by the mod_rewrite logic until I thought I have overcome, the "by the way" has cost my 4 days, and, stopped by the sessions lost while subdomain changed. In other views, I am costing my time to make up one lost lesson that how to administrator apache well. IN high percentage I am actually one excellent java developer either with database plotter, the administration work is not my major field. But lack of adult administrator I have to make it by myself, until I thought I have met its most then pass it to some apprentice follow. I have been the adult administrator of linux,database and dns administrator,even network and security, but just apache, I used to it for years, but few chance need to understand it, until this time.

That is why I intend to make the apache clear in mod_rewirte/subdomain issue before another issues continue, I need to know at the begin how weapon in fact I got.

I need to confirm the ways how to provide subdomain for modules , how to provide subdomain for members, and how to provide hardlink for SEO.

For the pages/SEO, the mod_rewrite can do it good by pages rewrite., but it is limited. its setting is too plain to provide funtionality logic, so that it can not support too complicated rewrite, especially it combinded with tomcat, the dynamic contents provided by tomcat rather than apache itself.

for subdomain of members, it is not suitable case for VirtualDocumentRoot, it will disable the similar virtualhost setting, or others else. The mod_rewrite is much better.

for subdomain for modules, They will all affected by the session/lost by simple domain name access.