Genetically a frizzle is not a breed; it is simply any chicken with frizzled feathers.
Not so comprehensive as to be complicated, Storey’s Guide to Raising Beef Cattle is still complete enough to be a useful guide for beginners.
Upgrading refers to crossing two livestock breeds with a specific purpose in mind—improving one of the breeds.
If you are looking for a basic guide to purchasing and caring for sheep, try Sheep Production in Kansas. Old, but by no means outdated, this PDF bulletin is available for free.