First of all, I'm trying to figure out exactly what the point of a child portal is.

As far as I can tell, out of the box, a child portal:
    has a seperate user base (can be fixed by a third party solution, I know)
    has to have a friendly URL set up for it so that the URL resolves correctly without the ?Alias=JibbaJabba on the end
    Only allows the admins access to modules which are defined\installed by the host
    Can be set up timed basis if so desired (monthly subscriptions for example)
    has completely seperate menuing and pages than the main site (and cannot be linked to as an on-site page from the parent portal)

Now that I've listed out my understanding of child portals, am I wrong in my understanding?

So, onto the second part...

What I want to do is have the ability for 'moderators' or 'section-admins' to be able to update content\reskin\etc pages within a certain 'area' of the site.  So, for example, if my path looks like MySchool.com\grade\11\etc\, then the Junior class officers need to be able to admin that pages underneath it.  Or if it's MySchool.com\Depts\Civics\pages\ then the appropriate Civics teachers need the ability to go in and make changes, to a certain point, and then only a specific teacher or say the dept head would be able to make changes to MySchool.com\Depts\Civics\Teachers\Mr.Smith\

I'm pretty sure this is beyond the functionality of the admin or roles at this point, but has anybody had any experience in doing something similar or knows any 3rd party solutions which may be viable?

Thanks,
Brian

Child portals are for related topics which are different enough to be a sub page. An example I use for my clients is this: A wildlife rescue site might have a child portal for ocean based rescue, one for woodland rescue, and one for domestic rescue. They all share the same general theme but each have a need for completely different navigation and seperate content. HOWEVER, you want one common login for all of them, where you can manage all the "subsites" from a central location.

Now what you are wanting to do can easily be managed by creating user groups and roles to control access to different content. IE only the director has rights to edit the departments pages and all the pages under the department, yet Mrs Smith has access to her biology page in the science department, but that is the only page she has access to.