In answer to your questions:
1) Vantage is a stand alone theme, not a plugin.
2) Yes, you can allow users to place listings either for free or at a cost - you can also allow businesses to claim their listings for a fee.
3) Vantage doesn't separate listings by location as such, although users can search locations, but if you are looking to take it further so that each location has its own set of listings you'd essentially want to look at a
WordPress multisite setup so that each location has its own instance. Additional customization would be required if you were looking to set up a landing page or something similar. Whilst AppThemes doesn't offer customization services, we do have a
certified partners page where you can find developers for hire who are experienced at working with our themes. Thanks.