I'll underline the main differences, but it's on you to dig dipper and read up on both.  

We purchased a lot of properties in independence-we go off of the school districts mainly.

Mainly, in my last experience, I found not going through a realtor much more efficient, since I was the realtor.

If this is no interest component, you need to impute interest. 

The main one is the AMI.

Keep in mind that property taxes are high in Grand Rapids (close to 2%), landlords typically pay for water, and repairs and maintenance costs are higher in Grand Rapids than other areas because you're dealing mainly with properties built in the early 1900s that require a lot of upkeep. 

However, my main question (which may sound dumb) is, “in this scenario would it be better to Refinance the house, or go through with HELOC?”

I wanted to hear some stories of challenges people have faced who have already invested out of state or out of the country before so I can know what to avoid, what to look out for, and where to focus my energy.I am investing in mainly single-family homes and small multifamily (2plex-6plex) homes with long term tenants.Cheers!

I do have the owners name and pay for a skiptracer to make it possible to find their contact info and have enough confidence in myself that I can cold call them weekly or monthly as my main means of marketing.

It's a combination of foreign money, mainly from Asia, where buyers pay cash in a hot area.