If so, adding an ADU would disqualify you from FHA lending depending on how many units it has.  

Well, that will depend on a few external factors like market, rates, capital access.I looked into the Boise market for my clients. 

Other than the actual neighborhood, it depends on if it is sailboat access (draw bridges or no bridges) or what the clearance on bridges is which of course determines the size boat that can be used.

In terms of your first property being a BRRRR or something turnket, it really depends on your market.

Make sure you have the money to replace it when it fails. 4.5k is low - could be up to double this depending on the ease of installation.Electrical, hvac, chimney, needs their own inspection done by the contractors to determine exactly the cost.

It depends on whether you are using current investing methods that include a bank or if you are using creative financing.Here is the difference.

Depends on the tenant.

Internet. 

Are you walking properties or doom scrolling the internet?

@David SchimanI think it mostly depends on your level of expertise in real estate.