Don't get me wrong, I would have LOVED if this Deck was 40 new Sea Serpent cards, but I don't see them going past the standard 5. But yes, it is possible this set will switch it up a little with an extra new monster at the expense of a Spell or Trap.
I don't think he does qaqa. Their names on the wiki were changed to Atlantean and plus sea is a pretty big place, there is room for more than one leader especially if this is atlantis. Though that brings up a point of them not using ALO effects since it pretty much is Atlantis.
[::[_]::]Common sense [+[_]::]just because you can doesn't mean you should
That Atlantean Armed Soldier actually looks quite powerful...
1. Summon Atlantean Armed Soldier to summon Deep Sea Diva or vice versa
2. Spec another Sea Serpant from deck or hand, depending on the one last summoned above (or Gemini Summon "Gemini Lancer")
3A. Easy Synchro.
3B. New Rank 1 or 2 WATER Xyz for the above two (if not in the deck, later)? Assuming that Atlantean Armed was a material with Deep Sea Diva, you could send it to the grave for not only the Xyz's effect, but destroy something on the field (still sent to the grave for a WATER monster's effect, right?)
3C. Atlantean Dragon Poseidra.
Also would like to point out that a lot of powerful WATER cards can send it to the grave as well. Brionic, Gungnir, Divine Dragon Aquabizarre (to also bring field spell back to hand) and Abyss Soldier come to mind. Brionic and DDAqua are also both Sea Serpants, fitting with the deck theme.
How many lasers does it take to open a bank account at McDonalds?