The calcium carbonate comes from the worms digestive system. Thermal compost will not have the added calcium.
I have posts all over, but basically I'm using the Clackamass Coots mix and the BlueJayWay watering schedule.
It's been a journey for me and I've only been doing this method for a few cycles. I started off with an organic coco mix (Fox Farms Coco Loco) and the Biocanna organic line of nutrients (Vega, Flora, Boost, and Rhizotonic).
I was recycling, but not reamending, and got into fermented plant extracts. Followed the methods on theunconventionalfarmer.com for a while with decent success.
From there I got into making my own soil and no-till methods. And started my own worm bin.
I read these three long threads:
Plus many of the recommended books:
One Straw Revolution
Seaweed and Plant Growth
What a Plant Knows
Botany of Desire
The only thing I learned in college is how to teach myself.