If you use most or all of a HELOC line, it affects your DTI. 

The JRADU will rent for anywhere between 1500 to 2000 so it will cover most or all of my house payment.

Work your numbers so that you your combined loan to value ratio (first mortgage plus second mortgage/after rehab value) is between 60 - 70 % so that you pull out some or all of the money that you put into the deal.   

And more importantly, is this a fireplace that only serves an ornamental feature (like in my house, 90% of the heat goes straight up the chimney and doesn't do hardly anything compared to the forced air heat) or is it a serious wood-burning furnace that can largely replace a gas furnace in some or all of the house?

With that said, in my market if you can BRRRR and pull (ReFi) most or all of the upfront cash invested and cash-flow $200 per month that's a d**m home run. 

Either for repairs, discounts, credits or all of the above.

What you need to do is trace a path from where you want to be (100 doors), and reverse engineer the steps on h ow to get there...step by step...until you arrive at one or all of the options you mentioned. 

Or all 3.

Unless you are flipping, you are not going to be selling a property within a few years of purchasing it or all your money will be going to realtors and lawyers.

We have inherited numerous tenants living in properties with an oral lease with the seller and have bought properties where the tenant names were not even completely documented-- all they had was a first name and an oral lease (jodi, apt. #1, 375.00, tommie smith, apt #2 ) We have tenants where the original lease holders have moved out and left adult children who never signed a new lease.