Select all polygons including a specific point.

Hi,

I'm a little bit lost...

- On my website, I've got a content type A. It contains an address field and a Geofield field, linked to the address field. Classic so...
- I've got a view that retrieves a list of "locations" (points so) (This is a proximity search, from a given city, eventually with a radius).
- I want to create a second content type. It will contain "dealers" let's say. For each of them, I want to be able to save the region they are willing to ship things. For example, "We ship in a radius of 20 km around Paris".

Questions:

- Do I have to save a "polygon" to save this information (to save the area my dealer is able to ship merchandise) ?
- If so, how can I fill this value ? How can I say to the dealer: " Now select the area you are able to ship". Do I have to use the "location map" ?
- Then, can I use Views to get "all dealers shipping to point X" (where "point X" = 1 result item of my first search) ?

I'm a little bit confused...

Thanks a lot