Heya Kammak...
You're on the right track mate
Your assumptions about the leader dying and referring the the group by:
group hSquad3
are right on the money.
However, if you have your second line:
hSquad3 = group this
in the init field of
any unit in that group, you will
always be able to refer the that group with that handle.
Even if
all of it's units are dead.
There's no need to have that line in every single unit's init line, you only need it once
Also, if you're after a way to specify the leader of the group (maybe you want them to make a radio call or something) you can use:
(leader
groupname)
This way you don't have to worry about which units are still alive, as it will automatically select the current leader.
Hope that clarifies a few things