For FRS & GMRS, all channels/privacy codes are the same regardless of band. That's FCC rules.
Technically, last time I looked several years ago, you needed a FCC license to operate the GMRS part of those little radios. But the license was nothing more than a $75 mail in card. :/ Not at all like my Ham Radio license that I had to study for.
As to who can attach to those type radios . . . got me. I'm wondering about good bike coms too. But as I don't have any $$ to spend, probably for the next year, I'll have to wait.
'07 BMW F650GS :) His name is Mith.