A) Well why should you be? Since you're making them for fun might as well show some people.
B) Again, same as A. Plus, they could give you tips on how to improve.
C) I can understand why, but then again same as B. Criticism can be a catalyst for success.
D) Some artists perform better in certain conditions, that's why you need to know when you work best, so you can churn out the better stuff as opposed to the late-night eldritch horrors.