What are important papers to secure after buying a land/property?

It's a blessing that I came upon this page because I have been wondering who to consult with regarding my problem. This is the first time my family is able to purchase a property of our own, so I am hoping that you can help me answer some things not clear to me. A relative in my father's side subdivided her land into 13 lots, and we bought lot 13. I haven't seen any documents presented to me by my aunt yet because my father is the one mostly doing the negotiation, except for a certification that's personally written by my aunt stating that she sold lot 13 to us. The certification was signed by 3 witnesses including my aunt's. I learned that my aunt doesn't have the declaration paper in her possession and that we need to secure that from the registry of deeds, I'm not sure if it's the right term. Although we only have in our possession the certification, I am not seeing it as a problem (or should I be worried?) because I trust my aunt and buying the land is a sort of favor for her since she's suffering from an illness and the money is a huge help for her medications. Anyways, the land will be surveyed this coming Saturday and each of the owners of the subdivided lots will have to pay 6,000.00 for the surveyor. My questions are as follows:

      a) Is the amount 6k for the surveyor not too much?
      b) What are the documents that the surveyor must provide us    after the survey (declaration, etc.)? How long does it take for the surveyor to produce the documents?
      c) What are the documents that we need to secure from my aunt so we can process the title of our property?

Thank you so much for your time in reading my post. I am really hoping that you can help me with my questions. God bless you all!