Unfortunately, I don't have any good recommendations for survey texts or anything like that; anything I'd suggest would probably be more one-sided than Wikipedia, anyway.

A deal of this size would typically take 2 to 3 months to close with the best time and if survey, title, other issues had to be worked through up to 6 months.

No survey, no subject to inspection, no home warranty.

Do a rent survey including use of a Rentometer to determine market rent.  

They then got approval to develop the land & went ahead surveying it & dividing it into lots, complete with ancillary roads & utilities.

The city engineer probably wants a site plan to determine no encroachment and not on an easement of any kind, I'm very surprised they ate telling you you don't need a permit for a concrete retaining wall, usually under 30" you don't need an engineered wall, but still require permits and an updated survey.

No utilities on, no survey, purchase is as is and so on.  

Get a survey, run title, lien search, environmental report  If everything checks out you should be in position to close (assuming you have the equity required) 

Thank you but we have already had it surveyed and divided just nothing transferred.

For example, if the land is worth $50k, and your building a 2000ft2 duplex at $110/ft2, and you have soft costs (design, surveys, permits, etc) of $10k, your total cost would be $280k, which most banks will be looking for 25% cash or equity = $70k, which means you will need the land (free and clear) and another $20k in cash.