I am interested to know, what tool or tools or even steps do many of you experienced investors rely on when analyzing the numbers to determine if the listing is worth contacting an agent for a showing? 

Since I'm not buying properties in cash (nor willing to accept a commercial rate for a conventional deal) I am doubtful of deeding property to a Holding LLC after close - it seems risky (and wouldn't that pierce the corporate veil already?).

looking at a 6 unit in NorCal excellent credit score, solid cash flow  

One a Heloc rate is much higher than a typical cash out refinance rate even if your first mortgage rate is low more than likely 3-4%.

Which is more rent reliable, best growing, both for cash flow and long term appreciation?

Don't bank the deal on getting cash back in a refinance.3.

This would surely put me in negative cash flow of $2000/month.

The house needed around 30k worth of work and it appraised for 212k after renovation was completed.

The home is worth $1.3mm today, and I have $700k remaining mortgage and $600k equity in the house.

If you’re looking to escalate as quickly as possible, it may be worth looking into a multi family and rent one side, and live out of the other.