I have run the numbers and it will cash flow really well, but my question is wouldn't that put a tremendous strain on me only owning half of the duplex. 

Your RE investments should not put a strain on your personal money, and vice versa.Other than that, which you may have already taken care of, I wish you the best!

Just because windows are single pane doesn't mean they need to be replaced. 

There have been growing pains--affordability concerns, strained transportation, low housing inventory, homelessness, sprawl vs. density--that will carry on in full force this new decade.

I’d say the best time to do a rewire is when your panel is somewhere it does not make sense and you find a proper place for it... then rewire.

Did new flooring at the time as well as replaced Sheetrock with drywall, new pipes, kitchen, double pane windows, and HVAC system.Plus 5-6 years ago put a new roof.Based on 3 comps I pulled the ARV of his house is $553k. propstream says valued at $581k.

Did new flooring at the time as well as replaced Sheetrock with drywall, new pipes, kitchen, double pane windows, and HVAC system.Plus 5-6 years ago put a new roof.Based on 3 comps I pulled the ARV of his house is $553k. propstream says valued at $581k.

The interior has new carpet and paint.The exterior has stucco and dual pane windows.

Of course this depends on where the electrical panel is and how much of a pain it will be to do this.

So even if the probably will appreciate a lot in 5 years, but keeping it may put constant strain on your young family.