First of all, Welcome to the DIS!!! You will find lots of great information and friendly folks here.
No, you do not need to be a DVC member to stay at a DVC Villa. We are not and have stayed in OKW, BCV and the BWV. We love staying in the Villas. Disney maintains ownership of a small percentage of the DVC inventory which they make available through CRO for rental.
You will also see lots of information here on the DIS about renting points from a DVC owner. This is significantly cheaper than renting through CRO, but it takes a lot of trust from both parites, and firm plans. In essence, once you know your travel dates, you find a DVC owner that will rent you a reservation that they have made using their points. An owner can book their home resort 11 months in advance, and 7 months in advance at all other resorts.
Depending on the day of the week and the time of the year, each day "costs" a certain number of points. They price each point and you pay the total for the total number of points for your stay.
You sign a contract with the owner, and their is very little flexibility in the contract, as the owner will loose their points if you cancel. Most require at least a partial payment (if not full) in advance.
There is lots of information on the DVC Boards here on the DIS.
Have Fun Planning!