Please review my listing if you haven't yet settled on a place. I have one for sale now for $62,500 in an Equestrian Community. Cost just depends on how complicated you make it and whether or not easements/roads are available to both. A good surveyor can give you a quote on splitting things out and that is generally the first step.
Georgetown is a great place to live!
As for subdividing, depends if it is in the City or County, on zoning, and other restrrictions that may or may not apply.
Consult your trusted real estate advisor, City Council Rep or County Commissoner, and local Title Company.
Coldwell Banker United, REALTORS
Also, you would need a land surveyor and an appraiser to help you. Real estate attorneys can advise you as well.
Best of luck