It's my understanding that if your property is pre-1978 and you're disturbing x sq ft of area (think it's 6 for interior or 20 for exterior), then you must be lead certified or use lead certified contractors if you're reselling or renting, may be exempt for owner-occupied, unless your state offers another option, like a lead-free certificate after professional testing. 

Only 1 sale in a year would be exempt and if considered a commercial property sale you are also exempt (these regulations really focus on sales to individuals for their personal home.You don't sound super motivated so I'd let the buyers do their own due diligence - as previously mentioned.Sales Price, Interest Rate and Down Payment terms all work together so if they need flexibility on, say for example the downpayment, you can then up the interest rate or go to 20yr amortization.   

I also noticed the seller lives in the building because they are getting a homeowner's exemption. 

They would only allow a HELOC on one investment property, and they require it to be homestead exempt which you can't do on investment property, so it's a no.

October 2020 is also when the clock runs out on our 2/5 cap gains exemption.  

This may be resolved by now, just wanted to add that if they pull the "ESA" card (emotional support animal) it sounds like you may be exempt (landlords owning <3 SFH not leased by realtor are exempt). 

You should be eligible for a homeowners tax exemption of some sort.

Its tax exempt up to 250K and then 15% on long term gain . 

On paper the initial numbers look great but some of the properties I looked at do not allow for investors or have requirements that the owner must live in the property for a year and then only allow the unit to be rented for a maximum of three years without requesting a hardship exemption from the community association.

@John Newburg, whatever portion of your primary you elect to utilize "for business/tax purposes", be mindful that the same portion will be excluded from capital gains exemption, when selling your primary (afaik).Something to think about?