Girl Scouts in the US in grades 6 to 8 are called Girl Scout
Cadettes.
There are other types of Cadets, such as an Air Force Academy
Cadet, and yes, girls may be that kind of cadet also.
Yes, Girls can be in cadets, for instance: Air Cadets, Army
Cadets, Marine Cadets, Sea/Navy Cadets or cadets which are
non-military such as Girl Scouts etc.