We will accept staterooms for the exchange til about 30 days before we sail. If we have any that join after that it will be up to the individuals concerned. On our last cruise we had about 5 join after the cutoff date and some were able to add them to their list and others could not. Some do a customized gift that requires time plus a lot of effort and that is the reason we try to have a cutoff date.
It is totally up to you how the gifts are done. Some do a stateroom gift, others do something for the kids in the room along with something special for the adults - the only limit is your budget. Please don't worry if it is not much. I have received many different things from bookmarks, magnets, themed cups and coseys (those things that can go around a canned drink) and little bags of various candies. I have also received things that people have done that were state specific and also country (some past cruises have included new friends from Canada).
I have found a lot of threads on the DIS that give great ideas for the FE and gifts plus magnets.
These are the ones I follow and believe me there is a lot of great pictures and information. Be prepared to spend a lot of time on these.
This one is called Homemade FE Gifts (Part 2)
http://www.disboards.com/showthread.php?t=2907032
What do you make for your vacation
http://www.disboards.com/showthread.php?t=2179996
Fish extender gift ideas for the not so crafty
http://www.disboards.com/showthread.php?t=2473209
Fish extenders?
http://www.disboards.com/showthread.php?t=1219607
Homemade FE gifts photo thread
http://www.disboards.com/showthread.php?t=1980639
Fish extender gifts
http://www.disboards.com/showthread.php?t=1774643
These are two individual posts that give the basic concept behind the FE and the directions for the no-sew FE. I have made 2 and pretty much followed the directions with a few modification to suit me. Any questions please let me know and I will try to help. I am in the process of making another for this trip. My first one had four pockets my last one only had two pockets and this one will have three pockets.
FE 101 Basics
http://www.disboards.com/showpost.php?p=33184281&postcount=2
Directions to make a no-sew FE
http://www.disboards.com/showpost.php?p=30302583&postcount=609
This is a great one for magnets and milliepie (one of the disigners) is great! She has done a few for me and I will probably get her to do one for this cruise also.
http://www.disboards.com/showthread.php?t=2897587
This one is the Creative Disigns thread which has a lot of disigners that do a lot more than magnets. But most of the disigners give their photobucket accounts and such that you can go look at and get ideas and other things.
http://www.disboards.com/forumdisplay.php?f=105
I know I have overloaded you here and don't think you have to read all of them. It took me a while to find them all, so save them for future use, and I hope it answers some of your questions.
Again,

to the group and I look forward to getting to know you and everyone else in our group!