To tell you ...
There is nothing special in being a guardsman other than the beret
you wear.
A guardsman receive INFANTRY training, only that you have to go
thru GCC to obtain the Beret.
For Specialist and Officer, the GCC is more structured but still
varies from GCC to GCC as the syllabus is determined by RSM based
on guidelines by HQ Guards.
Sometimes, when the normal training program do not permit for extra
, RSM usually allow a informal GCC where the compulsory items to be
a guardsman are done by installments.
e.g. some 3GDS/7SIB commanders just go thru a 2 day summary
exercise to obtain the beret simply because the ATEC and overseas
training schedule don't permit the commanders to be away from their
company lines for too long.
another example is that one may have failed GCC, but he only
require to complete the failed items to get the beret without
having to go thru the entire course again.
For Enlistees, there is no formal GCC other than the AIT you go
thru after BMT. This AIT again varies from CO to RSM's
requirements.
Some SIR receive even tougher AIT because their CO is either a
guardsman himself or a commando. Therefore his expectations of his
man is higher thus wanting a tough AIT.
To answer the other questions, you may be a Guardsman in NSF but
later sign on in other arms.... you may wear your Guards Tab but
not the beret.
The Tab is to show you have passed GCC, the beret is to show your
vocation. But if you really want to follow SAF dress code, you are
only allowed to wear the beret of yoru formation.
So NSF time you are guardsman and you sign on as a Pilot, you may
still wear your Guards Tab.
FYI, Navy personnel are sometimes sent to GCC.