You'll want to incorporate interest costs on the HELOC while you're using it, but that will add to your holding costs in addition to utilities, closing costs, etc..

Bonus points if I can incorporate technology to streamline applications.

You also should be aware of the Pre Payment Penalties on this loan, especially if you are incorporating a BRRRR strategy.

I personally do not touch equity in my own home to incorporate into my business.

One thing to consider since you are a California resident investing is the compliance requirements for LLCs incorporated in California or operating as a foreign entity here - the rules here are different than most states.  

My credit union I work with will allow 1.3 million in debt or 5 properties before they want one to incorporate.

I don't think we owe $800 in CA, we incorporated in GA and have a registered agent in GA. 2.

I have been using them and the sourcing people they incorporated for a few years now and the accuracy of returned contact information has always been above 90%. 

Look at the articles of incorporation.  

Hello, the State to incorporate is usually the same where the property is located.