Animal fat is fine for biodiesel, but the hydrocarbon chains are longer, so it is slightly more viscous, and has a lower cloud/gel point. If you are in cold climate this can be offset some by adding kerosene. My supplier adds about 10% kerosene for my winter blend (I buy bulk) The PH, I believe is lower, so you use more lye to split the glycerine, but I'm not sure about that.
Oh, and I think the best thing to do is buy every book you can. You'll save the $100 in avoided screwups. A good read before getting into it is "From the Fryer to the Fuel Tank" by Joshua Tickell. I got it as a first read when I was considering it, but quickly realized it would be like running a second business, and made more financial sense for me to just buy the stuff. I run heavy equipment (it's GREAT for that by the way) so I burn a lot.