First dibs, yes, but if nobody is using the planes then they'll have their gubs taken off. Though I'm not entirely sure why people are setting up loadouts already, without knowing what the next mission is going to be. MMSs are good for ARTEMIS-assisted saturation fire, dealing almost-guaranteed damage to frustratingly agile opponents, or landing a finishing blow on an enemy out of flares; but they're pretty dang heavy and aren't very effective against fortifications or particularly tough targets like air cruisers, naval vessels, or Defender tanks (at least, not until you get up to the MMS-20, which can certainly deal a devastating blow to any of those).
regardless, fixed armaments sheet to account for spare weapon systems. There is now 1 extra pulse laser, 2 extra beam lasers, and 1 extra MMS-12.