I want to speak with a lender to see if we could borrow against our existing properties to put less money down, but I have no idea what the cost would be of 1) the land, 2) improvements on the land, and 3) construction of the home.

I understand there are other reasons to consider that are not in the equation, i.e. tax planning and long-term benefit, improving cash flow over time, and equity gain.

3 I keep seeing these "AirBnB is Dead" youtube videos.

I’d love to hear more about what kind of improvements were made to the property and how long the project took from purchase to sale.

Save religiously, improve your credit, and pay off any outstanding debts you may owe. 

Many YouTube videos and books on the subject will help, too.I found that practicing analyzing deals was very beneficial. 

Also, how're you improving the property while you're there to help cash flow when you move out? 

Between forced appreciation on general improvements on the property and the capacity to add an additional residential structure, the sky was the limit on value growth.

You need to find short-term purchase and rehab financing (i.e. hard money or private lender) to acquire and improve the property.

If I was going to improve on one thing, I could certainly tighten up my turnover process and make units ready to rent again a little faster or even advertise a little ahead of when they are ready.