There are down payment programs for duplexes, i have not searched or tried to do a 3-4 unit property. 

After the loan is drawndown I need to immediately start making monthly payments for the next 60 months.

The most important rule is to have the cash flow of the new property be able to pay all its expenses, mortgage, AND the line of credit back.

Ensure you collect a proper security deposit (typically one month's rent in Florida) to cover potential damages.Your plan to increase rent next year makes sense given rising costs (taxes, insurance, and maintenance).

do not use a line of credit for a down payment. 

On the lease, he'll pay me $100/m over my HELOC payment and all other expenses, including the refi cost, inspections, title work, etc... 

My overall goal is to generate monthly cash flow, and my current property might be a better rental option since it has equity.I’m also considering starting a business and purchasing the next property in the business’s name.

Maybe an outside the box idea would be to try to force some equity by making some improvements in the house you live in.

The basic reality is.....instead of using your extra Monday each month to pay back a heloc loan you borrowed to pay down your mortgage.....simply use that extra money each month to directly pay down your mortgage.  

Once approved the send to QC and the file is sent to closing.