Nice to see you're up and running! If you think that's a large convoy, you're in for some real treats
Some convoys can consist of up to 30 ships or maybe even more.
As for the commander problem; I think (not completely sure) that you can only edit your crew when you're in harbor. So if you were trying to edit crew when you were at sea that might be the reason it isn't working. Can't think of anything else causing that problem right now.