In areas with rapid and sustained appreciation, you can use the equity gained through appreciation to purchase additional properties.

You don't have to buy one, you can install an app on your phone that will accomplish the same thing.

Regarding insurance adding additional umbrella insurance is great idea. 

Despite no additional renovations being necessary, our efficient strategy and swift turnaround led to a same-day sale at $225,000.

So you have some great resources right off the bat, my additional Referrals would be too many :)

I heard that less than 20% down causes additional insurance fee? 

Removing it cost us an additional $5k over our estimate.  

If you think you are accomplishing something just because an all cash deal is PCF, it's an illusion. 

Is the portal that the landlord and tenants use an additional charge?

That would be a helpful addition to your plan as you would further reduce your cost of living.Also don’t forget from that $600 you are planning on getting in cash flow you have taxes, insurance, maintenance, capex, and vacancy to consider.With two homes, you may want to keep that extra $20k as an emergency fund rather than spending it on a third property and then be left with no emergency funds.