West Philly (19143 & 19139) is a very common area for this to take place.

I believe Costar pricing depends on what market area you want, but for a single license, I'd expect >$500/mo.If you're new to investing, I'd suggest working with an agent, at least until you better understand the process and common pitfalls. 

This is commonly called a reverse exchange or a construction or improvement exchange. 

A common issue is supply and demand effected by population changes, construction, economic issues, the job market and location.Personally I haven't seen vacancy issues at this time,  but I have gone through cycles of vacancy issues.

That's my best advise on it.It is quite common to have issues with permitting or with the removal of tenants so the lender will understand if that's what's going on.

Familiarize yourself with the types of properties commonly financed through private money lending and the current trends in your area.

I was on the HOA board of a luxury building in San Francisco and you would be surprised at how many people will let their dogs pop and pee in the common areas (killing very expensive plantings).

Garden-level or street-level ADUs are common in New York multifamily properties.

Myself and family truly loved the property and house; just want others opinions on if this may be a mistake to proceed, or does this appear common practice for the age and location (upstate New York). 

its called a Hypothecation.. quite common..