I'd like to explore card operated laundry to provide that as an option for tenants, to offset the cost of running the washer and dryer while I pay for utilities. 

A Local Realtor to the property can do a broker price opinion, cost varies.OR Pay for on of the 100's of AVM services

Hands off ADU addition will cost significantly more than $100k.  

I was thinking perhaps it would be easier to just bring a general contractor to walk the site and provide an estimate on all the rehab costs, rather than to find separate contractors for each specialized task.For those of you who have worked on fixer-uppers, did you bring a general contractor to walk the property with you and give an estimate on rehab costs?

Essentially he rehabs his properties to make them undeniably high quality (not just "good enough" for section 8) in order to generate a huge demand and thus be able to be extremely selective in his tenant screening process. 

We thought about doing a cash out refinance which would give us roughly 40,000 after closing costs.

This of course can prove to be a costly process!

Also, I know that by law real estate agents have to disclose if things on a property are unpermitted to allow the potential buyers a chance to back out of the purchase if it's too costly & the real estate agent who sold my friend this property didn't say anything about any of the 3 out buildings that are on the property.

So, acquiring the property for a $2,100 cost with potential earnings of $2,900 is acceptable in your evaluation, provided there is sufficient financial backing to cushion any potential setbacks.Thank you, Frank! 

As for cost, my nuclear-powered Duke Energy NC Residential Service (RES) costs $0.11661 per kWh.