Partly true SAN. Traditionally UK a/c numbers were what the ship could hangar. The US regard their flightdeck as the operating part of the ship, while the hangar is for repair and second line maintenance. The current US CVN are actually operating at something like 80% capacity in terms of a/c carriage (they used to have a CAG with ~96 a/c in the good old days of STRKFLTLANT). In some ways this actually helps them generate more sorties, partly because there is more room on the deck which reduces the need to respot after a recovery and partly because the plastic bugs are easier to service than their predecessors. They are beginning to feel the effects of retiring the KA6 and the S3 though - can't get enough fuel airborne for longer range missions.
As far as sponsons go on CVS, there are two good reasons they've never been done. Firstly, too expensive and would limit current dock access (although that will happen with CVF), but secondly because the ship would capsize.