There is a 9 month per calendar year limit on how long you can stay in a resort. There has been some discussion as to whether or not this is a Disney rule or a State of Florida mandate.
In years past FtW offered a "Winter Settler" rate for people staying longer than 30 days. It was a substantial discount, and in those days, there were over 200 sites taken by "snowbirds". Now that the rates change daily (higher on the weekend than weekday), fewer and fewer people spend the winter at FtW.
You have to book ressies 30 days at a time. On check-out day you need to go to the front desk & check back in for the next ressie. They will not make you move to another site. Just tell them when you check in the first time that you have multiple, back to back ressies, and they will be linked together.
We've stayed as long as 4 months back in 2002-2003. It was great!!