How do u select all rines at the same time? What's the shortcut key?
Also how do select them as squad??? What's the shortcut key?

Top of the commander view screen, alittle circle with a marine inside.

Press that and they all get selected apart from dead people that is.

I don't know of any shortcut keys (i don't think there are any), however, you can select all marines, and stick them in a squad.

Select the marines you want in a squad, hold duck (default is ctrl), and push a number between 1 and 5 to assign them to their respective groups. A little icon at the top will let you know that you have successfully assigned the marines to a group. To select these groups, you now only have to push their respective number, or click on their respective button. When they take damage, the icon at the top will blink red.

This can also be done for structures, however, you cannot select more than 1 structure at a time.

Furthermore, if you give a squad a waypoint, and not everyone in that squad touches the waypoint marker, it does not disappear. Waypoint markers are annoying to marines because they block thier FOV, and makes it hard to shoot stuff, so move the waypoint when you can.

you can actually bind a key to "select all" in the options menu. it's really QUITE handy to watch the marines health, to see who needs medpacks.

just do it right at the start of the match, select all of em by draggin your mouse and put em in a squad. (ctrl + 1-5)

Is it possible to bind it to Ctrl+A ?

I'm pretty sure that you can't set it like that using conventional means, but maybe if you got some kind of keybinding program...