I don't see why not except that squid cooks so quickly you'd really only want to show it the barbeque, IYSWIM. Overcooked squid is like chewing a rubber. You could stick some big prawns or chunks of cod on the sticks as well maybe - brush with a bit of oil and Bob's Your Uncle (or not).
God yes.Not kebabs though. Cut criss cross pattern into it, not quite all the way through. Marinate in lemon, garlic and olive oil. Throw an barbie when really hot (ie. coals glowing/white but no flame) for 60 secs or so. Fab.