Since you are using Allimentum I imagine your baby has reflux or some other digestive difficulty, so I would keep the bottles as close as possible to the way you make them at home. If you use ready to feed at home I would recommend using ready to feed at WDW. I would probably get the single serve ones and either put a nipple right on them or if (like us, although we did get away with using different ones on our trip with my first ds, we'll see how we do in december with my second) you use specific bottles that help with the issues too then pour it into that. If you use powder then I would get the dividers pps have mention. I don't warm the bottles, and stopped doing so with my first ds as soon as I found out you don't have to it's really what the baby prefers. Both mine would/will drink them straight out of the fridge. I'm sure you know that if you have opened ready to feed or prepared powder it needs to be refridgerated after 1-2 hours depending I believe on the brand and prep type. Ours is 2 hours, but we use the generic enfamil now. Fortunately, after trying the allimentum with our first ds it did not work (I say fortunately because as you know it's really expensive and smells really bad), so we ended up doing basic formula with oatmeal in it per the specialist, and that worked and is working for our second as well. But I digress...my point is you will need a way to keep it cold if you go the route of ready to feed and not the individual ones, and I would not recommend preparing powder until you are about to feed it or else you will need to keep that cold too. I also would not let it stay out as long as the instructions allow because you will be in the florida sun. If you do warm the bottles I recommend going to the baby care centers, or asking at a TS or CS place for a cup of hot water to put the bottle in for a few minutes. I'm sure you know that you should never microwave a bottle because you could get hot spots and burn the baby even if you shake it really well. I'm sure if you use powder and mix will room temp bottled water that would be fine. You know your child best though. My biggest recommendation would be try to keep it as close as possible to what you do at home, and if you are going to change something, try it at home for a week or two first to make sure your baby will tolerate it. Nothing worse than a baby with a tummy ache or who refuses the bottle while on vacation, esp if you don't have what they are used to with you. Also as a pp said on our last trip which was 08 they only had Good Start available anywhere on property because Nestle is a sponsor of Disney, so make sure you have more than you think you will need (the baby may drink more or less at a time due to changes in schedule and temperature, and may drink more in a day, or you could end up wasting some for lots of reasons) or be able to go off property to get more if need be.
Wow sorry that was so long. Hopefully there is something helpful in there. Have a great time on your trip!