We used a realtor that was well versed in land deals and also did some short platting in the area. She had a team of specialists that we consulted on. We had a builder, an enviro engineer, septic guy and maybe someone else, can't remember. The realtor negotiated a reasonably amount of feasibility and then we contacted the individuals in order of cheapest to most $$$. That way we could stop at the cheapest "no" if you know what I mean.

You want a Civil Engineer. They can produce a topographical survey for your site showing setbacks, etc. Note that your town may have specific limitations on developable area, interior sqftage etc.

Okay - civil engineer - I guess that makes sense. I imagine the builder I have in mind would know who to use for this.

In our county you need to dig septic perc holes to make sure you have enough good top soil to do a septic and where it can go. The front of our property looks like swiss cheese with all the holes we had to dig. Our county also has a well log on line so you can see how deep wells are in your area. Our area averaged 100 feet but we had to go down to 150. We have a 100+ gallon a minute well though so I am not complaining. You can call well companies that drill to get an idea what an average well in your area will run you. There may have been a wetland study done on your parcel at some point. Here they have to conduct one any time someone subdivides.