Unfortunately, this is near impossible without selling the property, rates are up and are likely staying high. 

Wife and I have high credit score and we are high income earners (her W-2 & 1099 for me). 

. $140 equity in our primary residence that we’d be open to getting a HELOC on (would love feedback on if people recommend this or not).Given our limited available resources for down payment, high home prices, and higher interest rates, is now a bad time for first time investors to enter the market?

You can find this at either low-end antique stores, or high end thrift stores.

The $200k makes no sense and I highly doubt that buyer closes on it. 

and get the real impact on your return from amortization of the loan, depreciation, and appreciation as well as cash flow. 

High net worth is likely all cash.

I thought that seemed high but I could be wrong.

As far as I’m aware, there are no permits for the initial construction of this structure, where can I look to verify this and if there are indeed none, how much of an impact would this have on converting the property into an ADU?

This seems high.