Is this even appropriate for a realtor or should I be starting with a certain type of lawyer?
There is significant difference between selling a farm (we might call ti vacant land) and selling subdivided property. The amount of investment and expertise required to take raw land, go through the subdivision process, to the point where you either have residential lots ready for builders or in fact start building and selling finished homes, is great.
So my recommendation would be to meet with a Realtor that has experience with vacant land and discuss your options. Do not get your hopes up too high. Land developement requires captial, knoweldge, experience, nad most of all, risk.
One possibiltiy is to look into performing a lot split, so you separate your home and lot from the rest. Then sell the rest as vacant land. Discussing your situation with a Realtor will help you understand the local market and what options are realistic. You could also check with the county or city building and safety office to see what zoning options are possible. Changing the zoning for land is not a simple process, hoiwever if they are building next door, you could probably find out what they did.
Normally a farm is zoned agricultural. To change it so Residential there will be a process that might give you some ideas.