Hello everyone! I'm new to the Dis, this will be my first cruise, and I'm getting married on
Castaway Cay!
Congrats on your future wedding

It sounds like it will be magical
I've answered a few questions below
Mine & DF, my parents, and my sister & her bf are category 11B GTY; DF's parents are booked in 11A GTY. Does anyone know what the difference is between A and B?
The only difference is location, location, location. 11B seems to be mostly on decks 6 & 7, while 11A pops up on 8,9, & 10. But you might also get upgraded, so you never know where you'll pop up

Our first cruise we were upgraded from a cat 12 to a cat 9, and our second cruise from a cat 12 to a cat 11 (not much of an upgrade, but a better location, that's for sure!)
1.) Is the pirate party the night of Castaway Cay? If so, I'm kind of disappointed because I wanted to dress up in costume, but on the plus side I get to party in my wedding dress;
Well, it being a brand new ship, there is no telling if it's going to do things the same way it's been done on the Wonder 4-nights. I suspect we won't know anything until the very first sailing. But if it is, pirate night is indeed on the CC night. You could always add a few costume items to your wedding dress, hike it up on one leg and call yourself the Pirate Bride
Is the Palo brunch the at sea day? If so, that would be the day after the wedding and we would love to use our included Palo ressies at brunch instead of dinner. I don't want to skip any of the restaurants for Palo, so I figure the brunch would let us fit them all in and be a nice start to our first day as a married couple.
I know I said we can't know anything until the Dream sails, but I'm going to go out on a short limb here and say that brunch will still be held on the At Sea day (it's the only thing that makes sense). Brunch is yummmmmmy. The only bad thing is people constantly getting up to get more food, so it's less intimate, but it's still fun! Don't forget all the great to order food. Sometimes people get so caught up in the buffet spread, they forget to make room for the "to order" pancakes...or eggs benedict...or chicken parmigiana...or pizza..or..or..or Drooooooool.
I've just learned about fish extenders, and I'd like to participate as well. Any suggestions for FE gifts or where to buy an FE?
I've never participated in the FE, but I know there are a couple of great threads about them on the main cruise board. It's loooong, but fun to read
http://www.disboards.com/showthread.php?t=1980639&highlight=fe
http://www.disboards.com/showthread.php?t=1219607&highlight=fe
Anyone have an opinion on Disney photography? No one in my family can take a good picture if our life depended on it, so we have to use Disney's photographers, and man are those packages expensive!
DH and I take terrrrible photos. But each cruise we've purchased a photo or two. As for the regular lobby ones that don't require buying a whole package: here's my opinion, which I can guarantee you will find someone who disagrees with me, so take it for what it's worth.
I really like the LifeStyle portraits (the ones in front of the all white screen, where you do more fun, casual, more natural poses). Just FYI: with those you take off your shoes. Those have always turned out the best and look more like the professional family portraits you pay someone to come to your home to take. I really dislike the photos in front of the other screens as I think they end up looking cheesy (I swear we had one that looked like a
Walmart photo-lab picture from the 70's).
With the Lifestyle ones, they are very good at posing people for the best picture (tilt your head this way, now up a little). NOW, there is one guy who does it that I loathed...dark hair, short little guy with an attitude. He seriously kept saying, "Suck it in sweetheart...suck it in honey" But didn't say a thing to my DH with the substantial beer belly!

Plus he was impatient, and trying to churn and burn through, so we just had an off feeling. After that, we always waited until the other photog was doing the Lifestyle portraits (petite girl with dark hair, very sweet). Aside from the attitude, her portraits always turned out better for us. I don't know if those two are going over to the Dream or staying on another ship, but I hope she goes!
I've seen great Lifestyle portraits where everyone coordinated the color. For that beachy wedding thing, we saw a great one where everyone wore untucked, sleeves rolled up, button-up white oxfords, jeans that were rolled up (like strolling in the surf), plus the barefoot thing...it was great looking!
Though to be fair, I don't know how a wedding dress in the white family would look with the Lifestyle portraits. If it's the exact same white as the screen, you might blend too much, and if it's not, either your dress or the screen will look dingy. If you want to do dress shots, I'd save it for the character photos.
But if you want my opinion as someone who did the bride thing, and helped plan manymany times, for wedding photos I'd definitely be happier paying for the private
DCL photog. I've seen some people posts their wedding/renewal photos that the DCL photog took, and they looked beautiful! Ah well, people seldom look as amazing as they do on their wedding day, and you want pictures of that! DH and I have never taken better photos, so I count my lucky stars every day we spent that extra money on a good photographer. Once that magical day is over, all you have left to remember it by are your memories and the photos.
Again, just my opinion.
Hope some of that helps. Best of luck to you!
Edited to add: I enjoyed reading this TR on a secret wedding at CC: wedding pics start on page 27,
http://www.disboards.com/showthread.php?t=1487443&highlight=wedding