In Nov the average high is in the high 70s, the average low (mostly at night) is in the 60s. It's the start of the dry season, so rain isn't as likely as in the warmer months. That said, rain in the summer around here is strong but short-lived (sometimes just minutes, book-ended by sunshine), whereas when it rains in the cooler months it sometimes lasts longer. Water temps are in the high 70s to low 80s.
You can see averages at the link below (temp and other data points).
https://weatherspark.com/y/20786/Average-Weather-in-Nassau-Bahamas-Year-Round
From a practical standpoint I'd say bring a sweatshirt or light jacked if you want to be out on deck at night as it the wind can make it quite cool. During the day it's likely to be very comfortable - but of course nothing is guaranteed.
I ordered these off of Amazon and designed ours myself. I think they turned out super well, and we got to personalize them however we wanted!
You're probably right that it would be the "hardest" part but Dole Whip is actually pretty easy to do at home if you have access to an ice cream maker or soft serve machine (you can get one for about $100 on amazon).
Dole sells the mix whole sale and you can get it on amazon. They call it "Dole Soft Serve" if you are outside Disney but it's the same stuff.
Easily the hardest part of the beverage but also attainable if you wanted to go the distance with it.
Getting on and off the ship is very easy at both ports. The only things you NEED to take with you are your Key to the World card (cruise ID/room key that DCL gives you when you board) and a photo ID for anyone 18+. A water bottle is a great idea, however, and you can also take off pre-packaged food. I'm vegan, so I frequently bring a couple of energy bars with me, just in case. However, food is readily available on Castaway Cay. We used these waterproof cases for our phones on our recent cruise, and they'll also hold small items:
People also frequently bring a day bag, either a backpack or fanny pack/belt bag/bum bag, depending on what you're bringing with you.
I somewhat did this after the boutique on the Dream made my oldest daughter cry as a result of my daughter not shampooing her hair properly, and the boutique staff not being able to identify lice properly, forcing me to DIY it myself while on the boat.
There might be an item or two more, but for the most part that is it.
Just keep in mind that the effort is wasted the instant the kid wants to go into the pool. We held off on doing the boutique until the last day of the cruise for that reason.
The hurricane should be long gone by then. The current track has it scooting by Florida on Friday, with the storm being further up the eastern coast by Saturday morning.
https://www.wunderground.com/hurricane/atlantic/2016/Hurricane-Matthew
That shows the current track. It should be long gone by October 10th.
Matthew isn't the one I would be worried about though, but rather Nicole behind him. https://www.wunderground.com/hurricane/atlantic/2016/Tropical-Storm-Nicole
Her current track has her whipping around, so she should be staying clear, but she's the one I'm keeping an eye on. We're shipping out on the 14th. Current forecasts show the island as being rained on, but I'm hoping they still dock and let us off the boat in the rain at Castaway Cay.