Do you have to pitch if you toe the rubber?

Answer 1

"Toe the rubber" is not an official Baseball term, so I'm going to guess that you're using this term to mean when the pitcher assumes the windup position. If so, the answer to your question is "No." Once the pitcher assumes the windup position (or the set position), he/she has three options: 1) pitch; 2) throw to a base (in an attempt to pick off a runner); 3) step off the pitcher's plate (rubber).

Rule 8.01 covers this and is quoted in the Discussion section for this question.