Exploratory Mission

[HakuroDK]

I read somewhere that it was 700g per person for the airship in Ishguard, just don't remember where.

I read the exact same thing. I think it was in the patch notes, but it was also said on Duty Commenced as well that you would need 700 gil to buy a Mission Ceruleum Voucher, which would take you to the Diadem via Ishgard. And I believe that was per person, not just one per party.

As for FC transport to the Diadem, it was one Mission Ceruleum tank per airship. I'm 90% sure.