Hi Todd
As Agnes mentioned, this entire website tries to cover everyone internationally with the surname Shirley. So yes, please look around and see if your questions are answered.
Coats of arms are tricky issues. There are really only 3 different Shirley families granted coats of arms. 1st) The ancient Shirleys of Ettington, including the present Earl Ferrers' family. There are no unknown branches of this family as far as we know (but we're still looking). 2nd) The ancient Shurleys of Isfield Sussex. This family supposedly died out in the male line, but the Shirley Association believes that a few sons of Sir George Shurley, chief justice of Ireland, are not fully traced and have possible descendants, and 3rd) The Shirleys of London who were goldsmiths. The Shirley Association is trying very hard to document the descendants of this family and we're making progress. We believe that the collateral branches of this London family (which do not directly share in the grant of arms) is potentially huge.
However, the bottom line is that while we all share ancestors with the surname "Shirley", we are not technically able to "bear" any coats of arms which have been granted to SPECIFIC Shirley families in the past.....unless we are their direct descendant.
In the old days, illegally appropriating someone else's arms could get you thrown in the Tower

Of course, the modern custom of putting the coat of arms on T-shirts and coffee mugs reflects a more casual treatment.
I hope that helps.
Ken