That can be done with this setting:
GD > Settings > General tab > General sub-tab > Show Advanced > Allow posting without logging in? > YES.
This gives only two fields. How do I add mobile/phone?
On second question: I got how to make form and send quote. But once we receive order, how do I add listing. Because each quote may have different requirement and it shall be difficult to create packages for each such combination. In this case since customer is paying, I shall make it mandatory for them to register and add their listing as per their order. How do I manage these orders on GeoDirectory?