You are exactly correct.  Both of Pepin's books are heavily-illustrated and provide step-by-step instructions on cooking almost anything.  "Larousse" is the theory, Pepin is the practice.

>How do I execute cooking techniques like sauteing and poaching, and which techniques are important to know?

Buy "Larousse Gastronomique".  Feel free to supplement with Jacque Pepin's "La Technique" and "La Methode".