Hey Amy {
nice name, by the way!}!
You can call 407-W-DISNEY and have your requests added onto your reservation.
And just in case you need it...here is the number for Caribbean Beach: 407-934-3400.
They will most likely tell you that they will put the request on your reservation, but can not guarantee requests.
I would definitely request that pack n' play too! A good thing to know is if you want the rooms to have a door connecting them in the rooms, ask for 'connecting' rooms and not 'adjoining'. Adjoining means the rooms are next to each other, but don't have that internal door to connect them.
I like connecting rooms so that in the middle of the night when my kids are still so wound up with excitement I can pop them through that door at the Grandparents and say "HEY, remember how you wanted to spend lots of time with them?!? I think it's a good time right now!". And then I get to have that glorious Resort bed all to myself without little people jumping on my head! I'm kidding, but hopefully you know what I mean!
Thanks so much for visiting with us here at Walt Disney Moms Panel, Amy! I hope your March trip is fantastic!