Once the theme was bought the updates will be free for life ;).
You can easily translate it using WordPress localization feature (edit a .po file). .
The theme has some alternatives to the big map. It has the Revolution slider, which you can use to add mulltiple slides or just one image with beautiful captions…
It might be because your PHP version is lower than 5.3, which is a requirement. Please contact your host provider and ask them how can you update your PHP. There must be a solution.
Users cannot buy listings, they can buy accounts, where they can post there own listings. They will pay for the account with PayPal.
the theme doesn’t support this feature. Users can only submit Listings from admin.