As far as agents, if you want a resale home instead of a new home. There are normally about 200 plus homes for sale on MLS (a Realtor database) and about 200 plus homes listed with The Villages Agency (non MLS agents). To see all the used resales you will need two agents. To see new homes, only a Villages Agent can show them.
On your own, you can do just about everything an agent can do as far as some research. Here are the 200 plus homes for sale on MLS, it's called Zillow.
The Villages Real Estate - The Villages FL Homes For Sale | Zillow
Here are the resales listed with The Villages
Homefinder - The Villages(R) Homes and Villas for Sale