The guest had brought additional guests than they listed on the reservation, doesn't respond to my messages/concerns, left my front door wide open when they left. 

Again, DM us if you'd like a more focused & faster/efficient chat:)

If the addition is not permitted, I would run away. 

Additionally, the city is actively encouraging redevelopment and attracting businesses back to the area.

You'll want to incorporate interest costs on the HELOC while you're using it, but that will add to your holding costs in addition to utilities, closing costs, etc..

My goal is to grow this business by expanding my investor network and seeking properties that will allow for additional scalability.

For example, if local regulations require energy-efficient upgrades, prioritize these changes to avoid fines and demonstrate your commitment to sustainable practices.Case Study: In 2020, many cities introduced rent control measures.

I do have additional coverage for the sewer since I knew it may have issues before I bought the property. 

It is common for investors to bring in additional signers, often referred to as credit enhancement.

Most of the time, an ADU will cost 100k just for that part and then you have to actually build the cosmetic part for an additional 40-50k.