I got most of my info from a book I got years ago. I haven't used soapcalc so I can't really comment on it. When I buy oils I tend to buy organic and fair trade. It makes for a more expensive product but not more that buying a store purchased product.
The palm oil would be used In stead of tallow. They are suppose to produce similar results. I have never used animal fat in my process so I don't know if it is true.