Hi!
It all depends on how these things are stored, but I will assume the most likely scenario:
1. You are looking for the taxonomy term filters for that. This documentation will help you with that. I also recommend checking the settings layout and visibility documentation.
2. I guess the location is either stored in a custom field (post meta) or perhaps as taxonomy terms. This documentation details how to use the search in custom fields, and this one for the taxonomy terms.
3. Suppliers are very likely stored as a custom post type, you should see it under the General Options -> Sources panel, there you can select it.