If this is a property purchase I'd make sure to double check the environmental piece in case there are underground fuel tanks that need to be remediated.

There's a few phases - For info for buying, you'll need Leases and terms, breakdown of costs (what is tenants responsibilities and what is landlords), breakdown of CAM (Common Area Maintenance), each units price per square foot, tenants revenue to rent ratioOnce you go into due diligence, you'll need balance sheets, surveys, P&L, and tenants' sales reports for two years. lease docs and amendments including any statement regarding oral agreements, tenant estoppel agreeing with what you've been given, any open permits or zoning issues, environmental reports (don't want to find out later an old gas station or laundromat was there before), owners current budget, a complete list of all property stating who owns what and who is responsible for the care.

The violation or enforcement of those portions of any law or government regulation concerning:a. building;b. zoning;c. land use;d. improvements on the land;e. land division; orf. environmental protectionNow I haven't seen or read the OP's so I don't know if it's an HO's policy or if there is an exception to coverage which might affect the underwriter's liability if it's otherwise provided. 

I created this post out of curiosity about my generation (I'm 19) and our current and future footprint in the world of homeownership and real estate in general.

. $4300 sounds insanely high to me, to put it in perspective we pay less than that for a 5 unit in with commercial footprint in a floodzone... 

A coach house could be 700-1400sq feet as the footprint of the CH has to be 700sq ft, but maybe some builder creates an affordable CH design for the inevitable demand coming.This should increase property values of current owners even if they haven't utilize the conversion or CH because a future owner could monetize that.

If you have anything under 100 units, you definitely want to find a property management company that has a large footprint within 15 miles of your property. 

@Sue HoughI actually was an environmental engineer looking to get in to the solar industry a few years ago.I absolutely LOVEEEEE the solar tiles.

Any QI with a national footprint will be able to help you out since 1031 is a federal statute and we perform it the same in every state.

Then buyer negotiates game room above garage...so that adds 400sqft to the build....legit...it is there, not added on after, no size added to the footprint, building lines, etc.