First off, welcome to these boards. We hope you will learn many wonderful tips here. We sure have over the years.
As for the Valor, yes the rooms are numbered. There are little numbers to the side of the doors. Kind of like house numbers. And there are also little mailboxes for notes, etc.
As for the doors, yes they are metal and magnetic.
We sailed the Valor last year and yes, the doors all look the same when you enter the hallway.
We had 5 families traveling together and a total of 7 rooms. We brought magnetic white boards for each of the doors. This allowed the kids to leave messages for each other, etc.
We also have done tropical paper decorations using some specialty tape found at the party store (won't remove the paint).
This year we are sailing in July and I have purchased some very discounted holiday decorations for our doors. Kind of a Christmas in July idea.
Good luck and enjoy the boards.
Please feel free to let me know if you have any further questions regarding the Valor. Great ship and you will have a wonderful time.