Best (Fastest) Arithmetic Algorithms
The concept of a "best" algorithm is not as simple as you'd expect. It depends on at least two more parameters: the machine model and the numbers involved (i.e., how large are the numbers being operated on). For a thorough discussion of this as regards integer multiplication, see Fürer's paper How Fast Can We Multiply Large Integers on an Actual Computer?

There is a wikipedia page devoted to the computational complexity of mathematical operations, including everything you mention. However, from a practical point of view, I would rather look at the source code of a strong library for multiprecision arithmetic like GMP. Such a library is optimized for fastest performance on actual computers. The source code of GMP is readily available, and you can peek under the hood.