Can I pay in a plan, like for flatsales? No. This option is only for flatsales, the winner of the auction must pay within 24 hours.
What stages will Cerena be drawing? She will draw all but the first stage. So you'll get Messenger Reborn on up from her.
This is for a full custom? Yes. This means you get to pick not only the item that gets sacrificed, but also details about your Herald's physical appearance.
Is co-bidding allowed? Certainly. Just keep in mind that if we do not receive all the gold/items within 24 hours, the Herald will go to the next highest bidder.
Can we co-own a Herald? Eh...Sarielle isn't thrilled with the idea, but she won't definitely say no until it's proven it won't work. She does insist that ONE owner is named as being responsible if the Herald is neglected. So again, it's allowed, just not really encouraged.