Hey Sam - I was reading your other thread about the long distance rehabs and came across this. I see we're a bit outdated but I'd be happy to share what I know.
The subdivision process will vary from jurisdiction to jurisdiction and is therefore highly localized. Your ability to subdivide is also every bit as political as technical. What I'm sharing is based on my every day experience in South Carolina but my intention is to provide a broad enough reply that it would apply anywhere.
Your first resource is the applicable zoning ordinance. The property will have an existing zoning that will specify the use, permitted density, and any lot specific requirements such as lot size, width, and setback requirements. It is of course possible to re-zone a property or obtain variances, but my experience would show this is entirely a political issue and very loosely tied to what is strictly logical. Often the planning department staff will work with you only to be overruled by County/Town Council.
If you think your plan could be feasible, the next step is to put the property under contract. Land contracts are entirely different than your typical home purchase contract. In my area, it is typical to have a very low (less than 1% earnest money deposit) and a 90-180 day "Due Diligence Period". The Buyer has the right to cancel the contract for any reason or no reason during the due diligence period and is entitled to a refund of the earnest money.
The goal is to have your project fully entitled (subdivision approved) during the DD period. This eliminates all legal risk. Ideally, you want to develop land construction plans and have those bid during the due diligence period as well so that you can have an accurate budget. This eliminates 90% of your risk.
Professional developers NEVER close on non-entitled land.
You will need to hire a civil engineer who will do all the heavy lifting on this. In my area, the civil engineers are the experts on the zoning code. They will design the subdivision, work with Planning staff to get it approved, and can help with bid procurement and budgeting.
Typically, the land development process goes in this order:
1) Identify subject property. Do a "back of the napkin" budget to determine whether the parcel is worth investing due diligence resources.
2) Get the property under contract with the longest due diligence period possible.
3) Hire an engineer. Have them perform a "concept drawing". Run an initial budget off this concept to determine whether you kill the project at this point.
4) Hire a surveyor to do a boundary, tree and topographical survey. This is the first big expense.
5) Provide the survey to the engineer and have the engineer draw a preliminary plat of subdivision based on the survey info. (Pro tip - make sure your engineer approves of your surveyor before hiring them. Miscommunications between these two consultants are common and costly)
6) Obtain "Preliminary Plat Approval" or "Sketch Plan Approval" (your location could have its own name) which entitles your project and allows vested rights for a certain number of lots.
7) Run another budget. If you don't have the knowledge to do your own, have your engineer do this for you.
8) Now you can close on the property if necessary. Consider carry costs however and do what you can to avoid closing for as long as possible.
9) Have the engineer draw actual civil construction plans. This is your most expensive "soft cost".
10) Get the civil drawing approved. Depending on your location this could happen very quickly or take over a year.
11) Bid out the plans to contractor.
12) Perform the horizontal development
Feel free to hit me with any questions. Good luck!
Source: I am a real estate attorney by trade who now works as the land manager for a large development company.