1) I think that sometimes is difficult the for the user that is trying yo find a business.
If I have category A and B and if a have 2 cities A and B
Sometimes I try to find a business in city A in city A show that there are few business in this city but the page don't display the business because the business in the city A are in the category B or in A.
The numbers that display near the cities don't care about the category that you are and it make the number be confuse. In my opnion and thinking about usability the numbers that display in cities drop down should take care about the category.
2) If I'm under the category A and city A sometimes display a big numbers near the city like 200 business but on the map only show 10 business because the map only show the business that are in the fist page. It is confuse ass well
3) The map module should connect with category. The page should display in the map filters each category the user is trying to search. I have few categories and few cities and after to search the can forgot each category they are searching.