Q: Should I "use" kink as my emotional outlet?

Honestly, probably not, or at least, it should not be your only coping strategy.  In particular, highly emotional participation in kink scenes can increase risk, just as kinking while intoxicated can increase risk.  That is different from experiencing an emotional release from a scene, or from the connection with your partner(s) during kink activities.  Participants with high scores in this perspective tend to value that emotional release from kink, even if they do not "use" kink as a way to process or handle their non-kink emotions.

Q: Does a kinkster high in "Emotion" need more aftercare?

No, this perspective and aftercare needs aren't related.  If your partner needs more aftercare, that is something that can be esablished through communication and negotation, not the KPI.  We highly suggest reading this resource on aftercare.

Q: How does emotion relate to physical stimulation?

This is a very difficult question to answer.  On one hand, there is an obvious link between emotional responses and physical stimuli: a car just missing your own when you are driving will doubtless elicit a physical response (heart racing) as well as an emotional one (feeling scared or perhaps angry).  On the other hand, physical and emotional responses are not always predictably linked, as many in kink lifestyles can report on their pain/pleasure dualities.  What is important for this perspective is that the emotional component of a kink activity is more important to certain people than to others.  Those others may be more focused on the physical or sexual sensations, but they could also be focused on their character, their toys, or their partner.