(Previous rent was $1,300 but we're about to put in a brand new kitchen from the studs, new flooring throughout the house, new furance, adding A/C, etc).So do we just pay for it all upfront and mostly drain all of our savings, or do I let the rent pay for it and utilize our other savings to get a second property this spring/summer to increase our cashflow? 

Anywhere that one can buy properties for under $100k is very unlikely to have the rent increases that you will need over time to create positive cashflow, or the price appreciation that you will need to make this a profitable endeavor.

The state laws (do not quote me) appear to not let these companies increase rates (or its not easy) to pick up the losses.

Typically if demand increases and supply is maintained prices go up. 

If you can get your Vantage Score up 50 points, you will see positive results on the mortgage scores as well, it just may be 30 or 40 points or could be 60 to 80 point increase vs Vantage increase of 50 points. 

I don't know if I'm getting much appreciation on a duplex unless the rents are significantly increased.

The Raleigh market may have increased by 40% after the Apple announcement, but it wasn't because of Apple, at least not solely.

And this will only increase in my opinion so it's a great time to invest!

Pretty incredible how rapid the demand has increased in the past 12 months especially. 

That helps some...but your variable expenses also go up too - property insurance & taxes - so a lot of your rent increases go to offset rising variable expenses.I started at the age of 47 in 2018 and we bought properties fast and furious - 12 the first year, 10 the next, and 9 in 2021 and currently have 38 properties.