1. Is it like a URL shortner?

    Yes and No.
    While it is short 'link' to any point on the surface of earth,
    it is pre allocated to that point, not dynamically provisioned one by one.

  2. Is it unique?

    A wolo code is unique.
    The last three words though are unique only within that city.

  3. Does it work offline?

    While the technology does work offline as the codes are generated algorithmically,
    the current web based implementation does NOT have provisions for required caching
    for offline capability