Nautilus will probably a great addition to the Epsilon navy. They needed a heavier anti naval unit. I question why it needs to be a sub, though. Epsilon now has 4 submerged units and one 'ship.'
Mission additions yay! Lizard Brain sounds like a Scorpion Cell mission. And Dance of Blood. *heavy breathing* Give me Yuri's island! Other missions sound interesting, too. As always.
Well it's kinda logical, if it was a surface ship, it couldn't move together with other Epsilon naval units without giving away the whole fleet's position.