Is it better to keep adding equity by doing work on the houses while I'm renting them then refinance to recover the initial down-payment to reinvest into another property or to pay down the heloc?

This negative position can consume years of cash flow to recover.

I think behind tenant screenings and leases there is a quality of a landlord that's also as a person that is the respect for a good person and the intelligence of making fair affairs.
For me for ten years in the past...

Assuming you don't have a mortgage that requires a certain level of insurance, you can get a stop-loss policy covering all the properties. 

The tenant understands that the property of the Tenant is not insured by the landlord for damage or loss of any kind (action of third party, fire, water, theft, vandalism, storm, heat or cold, electrical damage, pests, mold, accident, etc.), and the Landlord assumes no liability for such loss.

As firefighters persist in battling the blazes, many residents are left assessing their financial and emotional losses.

Or just looking to offset the loss?

That being said, the only thing that being a QREP does is allow you to take losses against active income.  

This negative position can consume years of cash flow to recover.

Be mindful of a gift tax implications if you sell a house for less than FMV.Also be mindful of transactions between related parties when selling at a loss.