Do you save three months of vacancy for each unit and $50,000 for the roof replacement?

I actually decided against investing in Cumberland for the time-being so don't have any tips/advice regarding PMs and such out that way

You can replace the windows.

If so do you have any suggestions or tips for best practices to do this?

You said "100% of our funds were investors" then "my capital came from bank Lines of credit NO investors", so wondered exactly how much of the 100% was replaced. 

Now do not get me wrong, tech has its place in real estate, but it’s not a replacement for expertise.

On 1 townhome in MN I spent $17,000 for one reroof, $7500 for a new drive way, and $10,000 for a deck replacement.

Bonus Tip: If this quadruplex is out of state, I’d highly recommend building a reliable local team (cleaners, handymen, etc.) and maybe consider hiring a co-host or VA to help with day-to-day tasks, especially if you scale up. 

A couple tips--Always best to house hack small multis when you are moving around from base to base. 

Insurance-  replacement costs.