Pride is Edward, and believes himself to be Edward. Presumably the real Edward was going to show up later, and probably defeat him soundly since Edward's mere presence would cause him harm.
Sloth is Scar's brother. This wasn't really a secret, I just never found a good point to reveal it. I never thought of his power.
Lust is Hughes, and his power had something to do with manipulation of memories.
Envy, Wrath, and Gluttony are still alive, and were going to show up when Edward came back through the gate, or otherwise as they did in Conqueror of Shamballa.
Pride attacked and severely injured Izumi and Sig Curtis after they doubted his identity.
The real secret, now, was the identity of Greed and "the old man". These two are Nina and Shou Tucker respectively. This means the artificial human Shou created near the end of the anime became a full on homunculus. This was going to be a big reveal. Greed's power is to create doubles of herself by splitting her lives into separate bodies.
Their plan is essentially taking Dante's place as supreme ruler and alchemist.
