I have a HELOC on my Texas primary residence and am considering a house hack for my next purchase.

Investment Info:Single-family residence fix & flip investment.

@Kris TohovitisI wouldn't recommend using your cash to pay off the mortgage on your primary residence since you can likely get a better return on that money by investing it.What's your buying criteria for the multi-family property?

Land Use Codes and Building FeasibilityExample 1: Property Land Use CodesActivity Code: 4000 (Social, institutional, or infrastructure-related)Function Code: 1000 (Residence or accommodation)Ownership Code: 4200 (State government)Example: Regrid Property Example 1Example 2: Zoning DetailsZoning Code: T3Zoning Description: Sub Urban ZoneZoning Type: ResidentialZoning Subtype: Single FamilyOwnership Code: 1500 (Businesses and commercial entities)Example: Regrid Property Example 2Based on these land use and zoning codes, can I build a house on either of these parcels?

Investment Info:Single-family residence buy & hold investment.

@Heather Bailey When house hacking with a separate rental unit, ensure proper insurance by obtaining landlord or short-term rental coverage tailored for Airbnb activities, in addition to your primary residence policy.

In most cases, I don't recommend renting out your primary residence especially if you have no rental experience and that is because usually your primary residence was bought without the idea of renting it out.  

For example, the 2nd to last photo of a random wall and floor with part of open door; what is that supposed to be telling?

my condolences on your recent lost.there are a few ways you can do this, as mentioned above you can take a heloc on your primary residence which will give you a second mortgage, first mortgage payment wont be impacted. you can do cash out refinance which will give you one mortgage and payment. it will pay the old mortgage and give you money in your pocket to pay for the rehab.or you can do a renovation refinance which is similar to cash out refinance but we would contractor involved  as part of the refinancing and they are paid through the loan

If you own this as a rental then there is not homestead exemption and you'll pay much higher tax rate than a resident/owner occupant in SC.