Just because an attorney wrote or looked over the lease does not mean it is a good lease, is enforceable under state law, etc.

Building your own projections with what your realities will be is the only way to conduct due diligence on a property (ie property taxes based on a new assessed value, insurance, etc) As you stated, your financing scenario can turn a great deal into no deal pretty quickly.Further, it's safe to always assume that expenses are understated, even if it looks like the seller's due diligence package looks complete.

Single family units are generally exempt from age and occupancy requirements at that level but generally will come under state and municipal codes being the same or more stringent.

As I am sure you will find that the easiest part of the project is the rehab(which is probably understated).

Note that in many cases, expenses are under-stated by the seller because it makes their property look like it is worth more so they can sell it for more!

The rent growth reported checks out; we're seeing similar stats across a lot of the major secondary markets.The impact that COVID has had in pushing primary market residents (NYC, LA), especially young people, to the next tier gateway cities (Atlanta, Charlotte, Austin, etc.) can't be understated, as the urbanization trend continues but folks are having harder times justifying pandemic NYC, so instead they're competing on a fixed number of in these gateway cities.

Then a new buyer could add multiple ADUs with a limited exemption under state law

Normally under state law it transfers to the new owner on title.

(Don’t forget covid knocked out 6-8 weeks in 2020 so annual 2020 number might be understated).

Average Morgage rate in 1980 was about 16.5% average last yea was around 3% if you borrowed 800K at 3% interest you pay 24K the first year in interest if you borrow 100K at 16.5% that’s 16,500 officially which I believe to be understated the inflation amount since 1980 is 240%. so the interest equivalent for 1980 for a house would be 39.6K in interest compared to 24K today or around 40% less expensive for a loan.