I'm also building an ADU here at our primary that we'll operate as a STR. 

@Tony Ferreira what do you have for savings, do you own a primary residence and where are you looking to buy?

I, as the new homeowner, am actually moving into this home as my primary residence.

Will this property also be your primary residence?

I took a HELOC on my primary residence for $200k.Used 35k down, 12k burned by a nefarious “contractor”, we eventually obtained a real contractor who did amazing work, got it rent ready and cost about roughly same amount as the first and finally got it rented.

Most of the area it’s only allowed WHILE you are living in the unit as your primary home.

S Corps primary function is to reduce self-employment taxes, and rental income is not subject to these taxes.

I also have a primary residence with nearly a JUMBO loan at a high interest rate and I own a vacation place in cash (small trailer not worth much money but i also own the land) in a different state that I pay RE taxes on. 

However, given that the STR it is technically ‘attached’ to my Primary residence, could I still offset loss years against my W-2 income?

You would need to live in the property as your primary residence for at least 2 years then sell within 3 years after that (must have lived in the property for 2 of the last 5).