Environmental issues. Contaminated land is what springs to mind when environmental issues are mentioned, but in this scenario, what is most likely are potential flooding or drainage problems. A history of flooding or waterlogging is clearly not going to be welcome news for a developer, but equally if the land has been used for potentially contaminative uses in the past or is near to sources of contamination, remember that remedying any actual contamination is costly and will significantly affect the value of the land. Any past surveys or reports that have been carried out should be to hand if required.
A really rough guideline that alot of spot-lot developers use is that the land should be somewhere between 10 and 15% of the sales price of the home. So, if the homes on ten acres were selling for $1 million, the developers were likely paying $100-150k for the lots. The home on your lot would likely sell for substantially less given the smaller lot size, so expect less for the land sale.
Your buyer profile can depend on what type of property you are selling, whether the land has been developed already, its location and market conditions, among other criteria. Is your likely buyer an individual looking for a lot for a new home? Or is your buyer going to be a builder or developer looking for land for their next project? Or is your buyer some combination of those, or someone different altogether? There may be different buyers for finished lots, rural acreage or a parcel of suburban land in a thriving new home market.