I am personally buying a lot in Casa Grande, Arizona.

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 use partnerships to help me fund my projects when it is hard to get financing.

By the time you do that 4-5 times you should be able to have a paid off home or excess funds to invest in other assets.

Marketing to find what is a deal, $$ to fund that many deals along with utilities, mortgage payments, taxes, cost overruns, etc.

Why isn't UN or any government funding it? 

Find a sponsor, reach out, tell them you're Canadian, they approve, review and sign LP docs, wire funds.

If your Realtor is anything like me, they want to spend any marketing funds where the most eyes will be. 

Quite the opposite - I invest my personal money as just one more member, in each investment we end up doing as a club. 

I used a personal line of credit of $8k to invest.