Some newbie questions...

Hi

I'm very new to Drupal, but have a lot of experience with php, CSS, and javascript.

I'm wanting to use Drupal for a new project and just want to check that Drupal can do some of the key features:
Thanks to help in this forum I know I can give different member types different levels of profiles with nodeprofile, which is great.

The site is a catalogue divided into hierarchical categories and locations (country->province->city).

I've set up the categories as taxonomies, and installed the location module which handles the locations and makes integrating with Google maps possible, and it already has the areas built in.

My question:

I want to have two navigation routes: by category or by location or both. So a user can drill down through locations and then also filter through location. I can't quite figure out how to do this. Also I want to have the filtering in Ajax. How do I just get the results without the whole page template? Should I edit the theme to exclude all the page stuff is a $_POST var is present? Or is there a less hacky way to do it?

I also need to be able to give different administrators rights over specific locations. eg an administrator for the Los Angeles part of the site.

On that note, which gives more control: editing templates (which I'm quite comfortable doing) or using panels? I'm thinking that I can get it looking and functioning exactly how I want it by editing templates but it seems that most people use panels...