1) "Choose commitments" means to dedicate yourself to a romantic relationship. The advice here is to not only choose a romantic partner using your heart; that is, based on physical and romantic attraction ("chemistry"), but also to use your head, as if you are a parent or authority figure. Take an honest look at the person and see if he or she is a suitable partner. Does he have similar interests as you? Does he abuse drugs or alcohol? Don't let your hormones overrule your brain.
2) I'm not sure in this instance if they're referring to relationships in general, or specifically to sexual relationships. Basically, though, I believe they mean that if you have a problem with your partner, to discuss it with him. Don't wait for him to approach the subject, as he might not realize that you have a concern.