No, you should have taken the Knight.
What is the point of this

Nope. After Bxd5, white is completely winning.
Normally, play should continue 6... Kxf7, 7. Qf3+ Kd6 where white has a very threatening attack. Theory has shown that black can stave it off with near-perfect play and emerge with a slightly better position, but I imagine for a beginner that it's scary.
Also, nowadays, after 5. exd5, black's main choice has been 5... Na5!? wherein a pawn is sacrificed for a lot of tempi.

Hi, I was at the DC tournament (as an observer) as well. Congrats on your purse. You are now a professional chess player!!!!
As to your question, i'm not sure how to answer, your rating is high enough to know the best reply to Nxf7................Is Qh4 something you've been experimenting with?
b
I was in the quads swiss. Yes, I was experimenting I had never seen this before
I was playing a friend online here and he played