[Mediawiki-l] Userspaces and groups permissions

[Gabriele Barberi]

Hello,
I'm running mediawiki 1.5.0 and I would like to have four groups (sysop, 
bureaucrat, developers, contributors) where:
- sysop has full privileges;
- bureaucrat has almost full privileges (can create new users, edit and 
add new pages, but cannot modify pages owned by sysops);
- developers can add new pages and modify them but only on their own 
projects;
- contributors can only modify some pages.

In order to allow future upgrades I prefer not to install patches not 
officially provided by mediawiki.org.

Could someone tell me how to do it?

I would also like to create new projects/namespaces with subpages, but 
the documentation on meta.mediawiki.org is not clear about it. How 
should I do it?

Please save me...

Thanks in advance and best regards
Gabriele