This is an opportunity to confirm they have the expertise you need.

Be sure to have proper reserves on the sideline incase rehabs go over budget or timelines get extended.

., you might be cutting it way too close to really do anything. 15k is the bare minimum I suggest for reserves or oh no money on any project so that doesn't leave you a ton left to work with.As @Glenn Banks said, 203k is probably your best option because it's an FHA loan and you can do low money down and the reno is baked in, but the reno is complicated.

Also, if I save for a down payment of 10k on a property, how much more should I save for reserves, like if I can’t find tenants for 3 or more months and/or I have to fix something on the property first?

Make sure to compare the costs and benefits of using your HELOC versus keeping it as a reserve for unexpected expenses.Market Conditions: Research the Dallas and suburb markets to understand demand, rental rates, and appreciation potential for both 4-plexes and duplexes.

I recently encountered a situation that left me feeling taken advantage of and deeply disappointed.Upon expressing my reservations about the steep cost of their course $8k,  I was pressured into signing an agreement by their representative.

We have A LOT of money saved for reserves.

If you have an excellent credit score, 740+, have a DSCR ratio of 1.25, and can show reserves, you may very easily achieve a rate in the 7s. 

You've confirmed that I'm running the numbers right AND that an initial negative cash flow isn't unusual.

I understand Zillow gives estimates and is not always accurate, however,  I've confirmed numbers through the county Appraiser website.