My questions is this: Is it smarter to purchase a property outright vs. putting down payments on more than one property. 

I made the payments for over a year and just recently put rental back into my entity. 

There may be other options there.But, from a strategic angle, that is where a random guy on the internet jumps in and says "You might be able to buy the property from your mother on a Lease Option" that you make the payments and maintain the house with the option expiring on her passing date, converting back to her estate which you and any other heirs will inherit".

I can introduce you to my network of trusted real estate professionals.

Quote from @Clint Monroe: Trust those instincts – they're usually spot on.

However, it is likely that I will want to use my commissions to fund repairs, use as a down payment, or even cover expenses on these investment properties.

For a cash out most DSCR programs are going to require that the property has not been on the market for the last 6 months, but there are a couple who will allow after the property has been pulled from the market but will likely have a pre-payment penalty. 

~we are going to buy a duplex together and use my equity in a heloc for down payment as well as save another 20k per couple over next year ~wife and I (plus 1 kid)  will move to one side, His family to the other (2kids)~going to turn my house to a rental, with the eventual goal to turn my half of the duplex to rental as well (goal is 50 doors by 50 years old I’m 31)~Market is a bit light, i am considering and open to building duplex.

Can I claim any of the purchase / down payment on my taxes?

Be super careful if you aren’t able to make these mortgage payments out of pocket if no rent comes in or a large capex expense “suddenly” comes up.