In answer to your questions:
1. There is a map which appears by default in the listing form, so either they would need to simply input a less specific location, or you could customize the theme to remove the requirement for this field.
2. Registration is required by default in order for listings to be placed, so again this would mean customization if you wanted to allow registration free/anonymous posting.
3. You can find plugin suggestions in the
recommended plugins page which includes a suggestion in the form of the WangGard plugin.
4. Our licenses allow for use of the themes on multiple websites/domains, so if you were setting up an instance for each location you would only need one theme license to do this. Thanks.