The process is more or less the same its just that depending on lender overlays any 5+ unit could be subject to "commercial" guidelines and require and environmental test, different occupancy requirements, etc. just small things.

I am happy to hear that you decided to make a conscious decision to make this year YOUR YEAR.

Conventional lenders will consider a number of things before deciding to lend you the funds to acquire raw land, such as your experience, your net worth/covenant strength, property details (does the property generate income, extent of entitlement risk, environmental concerns, servicing capacity, time to development, etc), market conditions, and your plan for developing the land.

I did enjoy the long list of pitfalls though (e.g. environmental hazards)Tax Deeds are offer huge opportunities for gains and in most counties you can get into these things for relatively low money (compared to buying property at retail).

Some factors:Local growth initiatives designed to stem the overpopulation of areasOften misused Environmental Laws pushed by local residents in opposition of new development.New development opposition and reviews by local residents in the form of hearings, etc.Redundant governmental reviews by many different departments.Just a few things which came to mind that exacerbate the already messed up housing supply around the country. 

I have used Remtech Environmental in the past.

Lastly, but most importantly, the environmental impact of such a business I'm guessing will almost certainly depreciate the land value if the usage were to change as it would require clean up and perhaps remediation.

If it's a healthy property with low maintenance renting is a good strategy but environmental conditions is certainly a concern. 

I am very conscious of hosts/managers time and really try not to bug, but we had a few incidents with the water heater in Rome. 

There are a number of Environmental/Air Quality Testing companies in the area.