Specifically in regards to not having a window in the living room.Alternatively, would somebody be able to point me to good resources to look into regarding zoning rules / legal codes for specific areas?

Without knowing more details about the specifics of the project being proposed as it relates to your property, it's hard to say if there are any obvious big red flags that could negatively impact your property's future value.That being said, I would try to find out as much information as possible about the new apartment building's design and layout - the two big things I would try to ascertain would be the location of the garage entrances/exits, as well as the location of any outdoor amenity spaces (pools, terraces, dog runs, etc).  

Way too many Red Flags and lack of transparency.

The area I am targeting is a vacation destination that is rather seasonally resilient (working theory backed by decent to moderate research so far).If I can get past the zoning hurdle specific to mainly "wastewater" - referring to the collection of the toilet, shower, and sinks discharge - I want to purchase 10+ acres that allow me to scale to something quite significant in time. 

In this day and age, not having a online Prescence and clearly documented track record is just a huge red flag

even suburban submarkets are red hot right now in miami like leisure city, homestead, florida city you can still get infill lots one of the last few places in miami dade county right now. rezoning and variances you can do even better. if you are limited on capital ground up construction and land might be something to consider in miami in these submarkets.

In general ADUs in single family zoned areas add less value than the hands off cost to add the ADU.  

With 30% down your options are thousands of lenders.Why is it unwarrantable- master policy not enough coverage; low occupancy rate; HOA reserves; cannot be rebuilt or repaired; pending lawsuit in the less than 10 year after built for construction defect; flood zone with no flood policy...?

That’s what I see  So thats the contradiction is that. and thats the red flag for me....they live a debt free life but have a car payment.

What red flags should I look for that would lead me to see a property that has been sitting as an “unwise” investment