I have not read this series, but I am planning on it.
I think I have an answer for the 'bowling' pins. They are actually refered to at 'ten-pins' in nearly every source I could find, but I digress.
I think it is an 'in-house' joke for the artists for the comics. I did a google search on "batman ten-pins" and the third result gave me a hint.
In some bowling games, there is a batman...
James
