I would recommend you and your husband get on the same page about future investing goals.

Additional Resources to check, 'FYIs', in case you want to learn more about rezoning in the future)-Look up your address on the city's zoning map here to see how properties in your immediate vicinity are zoned.

So, my first caution is it would be healthy not to expect similar results on certain real property investments/deals in the current and near future cycles.That said, there are multiple considerations and clarity needed, before I would act on any investments with your equity.

Both properties have a substantial amount of equity that’s essentially sitting idle.Would it be a good idea to tap into this equity (through a HELOC, cash-out refinance, etc.) to fund future fix-and-flip projects or purchase additional rental properties?

I highly recommend you work with agents in the future.

@Sharvil Patel1 is incorrect because of 3.5 is prohibited in many jurisdictions or at a minimum causes insurability issues on future transfers.

Once I get to a point that it is making enough per month that I feel comfortable taking money out of the business that would be when I get to the point that it is worth have a specialist assist me in all deductions, credits, and future items that will help me to transfer from a W2 to working for myself fully.

You already seemed to conclude you are forcing this deal, I would agree unless there's a reason why this property will appreciate significantly in the near future and the 40 year amortization schedule allows you to hold on for that to occur. 

Good luck with your future endeavors! 

Focus on education, networking, and analyzing deals carefully to ensure your first investment sets a strong foundation for future growth.Good luck!