While it has been relatively good in terms of rates of returns, the markets have been red hot and finding the same type of good cash flowing deals has been difficult for now. 

I plan to stash 10% into a side account for any issues that arise.

Duplex has new roof, vinyl siding, newer furnaces and central ac.

seems high from JUST closing cost perspective on buyer or seller side (escrow+attorney+survey+prorated tax+ doc)... but again it could be very low depending on how the closing cost is being constructed (may be point or cost from both side etc) ..if you can give a breakout /pic of the closing statement then i can help 

If you’re looking for a duplex where the rent on one side will pay PITI for the whole building, you’ll be looking for a long time. 

On the hard money side at least, typical for this area is 65%-75% for cash out and 70%-80% non cash out. 

There seems to be a wealth of information and podcasts on people who start and manage syndications but are there any resources on the flip side - the investors who invest in syndications? 

The market is hot right now, so you will be in competition with all the other investors that have similar goals to yours.   

One of my side ventures is vape juice "mixing". 

I say that because we are in a very hot market and you can easily over pay for a deal just because you like the property.