Regions - when where the visitors are located matters

I have a need to know where the users on my Board live. Think in terms of states, geographic regions, shipping zones, or service area zones. I want to track this information and use it to

a) populate new read only categories using the defined regions
b) allow users to search for information and include the region as part of the search criteria
c) provide other information (originates from outside the Board) based on where they live
d) display the poster's regional info with every post as well as in their bio

I didn't find a mod like this so I'm wondering how difficult it might be to develop it.

Questions/thoughts:

1) Some categories/forums don't need to know the region. Others do. So would it be better to just get the region information at the time they register or wait until they want to post?

2) Within some of the forums that are region dependent, some of threads will apply to all of the regions so there needs to be a way for the poster to indicate if the post is for a particular region. I envision it defaulting to their own region but then allowing them to choose from the predetermined list of regions which includes an "All Regions" option. Potential problems with this approach?

3) I have been thinking about making the categories that are region specific read only. It would be nice to allow posters to post to them but I immediately see potential trouble. If a visitor posts to one of the regional categories then the post will need to indicate which of the non-regional categories it belongs to. This may become too complicated for the visitors to understand. It's one thing to give them one way to post and ask them to follow the rules but to provide two different ways may make it too confusing. Granted, it depends upon the level of sophistication of the users and in my case, they aren't tech savvy people.

Your thoughts on this would be most appreciated. BTW - within the short time I've been working with Punbb I'm quite pleased with it. Nice work and thank you.