HmJ_JP, that Q was about naval invasions. AFAIK a naval invasion cannot be ordered except as (a sort of) army offensive.You, probably, just click on an existing order, which starts to edit it instead of creating a new one - kind of wonky: I still do it myself nearly 5% of the time. Generally, it works exactly as you describe; I prefer to set up all orders then assign divisions, though.
Tried "H"? As for redirection: it works exactly the same as your move order (provided divisions actually at sea); except with naval transfers you always have to click port.
Thanks for answer re port-to-port movement.