I know that you can no longer deduct interest on a HELOC for "lifestyle" uses (ie paying off a credit card or taking a vacation) but you can deduct the interest if youre using the HELOC to, say, add an addition to your house, certain restrictions apply of course.I dont want to replace my mortgage with a HELOC and subsequently lose the mortgage interest deduction as a tax perk. 

Do you know if there are restrictions?

What if any restrictions or gotchas are there?

I was thinking you needed something to restrict street access in some suburban setting with multiple houses on the same street.But there may still be restrictions to look into, such as if the community has CC&R's (Covenants, Conditions and Restrictions)

As you've mentioned in previous posts, commercial is a whole other animal without those restrictions. 

If you are planning to do development yourself , you need to know that condo conversions are most advanced project construction wise, as you a have to do full gut work with underpinning, building addition in the back and adding new uppper floor to maximize sqf. so if you are not into contruction world , your need to plan that your construction cost per sqf will be on the higher side.Regarding waiting for 2 years or more , Zonning in DC is constantly changing, and it is constantly changing towards restricting development.Before you could do a 3 condo conversion in most of neighborhoods  and have high ceiling condo and roof access for roof deck as height limit was 40 feet for building. 

Does anyone have any idea on how they’re getting around debt to income ratios restrictions when they’re ready to acquire their 7th or 8 th property?

As a landlord you may set a reasonable restriction on number of people.

Both....however in commercial, it is restricted to residential type properties, ie apartment buildings.

If the physical therapist “use language” violates the chiropractors “restriction language” then the liability would be on you the Landlord.