DSCR won’t be the product you would use for ground up construction/ new build.

If you're intrigued by the idea of flipping - these deals can be harder to acquire, consider looking into how to cold call owners of properties so that they will sell to you directly or how you can find these deals and sell them to like minded investors looking to flip or buy rental properties as well. 

I would pull the 500K, to then monetize through yielded interest bearing markets, then pledge those yields to acquire the purchase power for the planned various down payments  

They will have a Jumbo product with 10% down with no reserve requirement up to $2,000,000

Propwire is free and a product from Jerry Norton.

Start talking to local lenders and see what kind of products they have for construction/ rehab loans.

He talks about how you can purchase a rental property, manage it as a short term rental during the year you acquire it, do a cost segregation study, use those "losses" to significantly reduce your taxable income that year, and then turn the property into a long term rental in the following year. 

The government saw the housing bubble and changed guidlines with fannie and freddie to make the 10 down / 2nd home loan product very expensive (about 4 points to close).

I am thinking about actively trying to grow my investment portfolio and use my existing properties as leverage to acquire more properties.

Because of the way they are valued, there isn't that much difference in the business plan for profitably acquiring and running these.