Many people disagree, but taking babies to WDW is fun. I too my girls right around 9-10 months, and I am taking my son next month when he will be 10 months. I'm also a DVC member....congrats on being a new member
Flying can be hard. On the return flight from her first trip to WDW, one of my daugther's cried the entire flight. That was hard. Typically, my kids do well with flying, but you just never know. Bring a bottle or nurse during takeoff and landing. My oldest slept during her first flight so it might happen if you are lucky. I also brought snacks and a few toys and an Ipad for the flight. I always do an order from a grocery delivery service for diapers, wipes, babyfood, formula, etc. It helps lighten the load with what you have to pack. If you use a pack n play, I bring my own crib sheets and one of the mattress pads for pack and plays, which makes it a bit more cushy. My kids are always so tired at WDW, I think it probably doesn't matter except for the first few nights.
Definitely bring a good stroller. We rented a City Mini when we took our oldest on her first trip and liked it so much we bought one when we got home. They are easy to push, have a great shade, recline, and have decent storage. I would also probably bring some type of baby sling or carrier to wear the baby if need be. I really like my Baby K'tan because it tends to be more breathable than some of the other carriers.
If you little one is on formula, bring extra. I thought I had on my daughter's first trip, but I think since it was hotter than at home, she drank more than usual. I ended up taking a taxi (pre-uber) to the drug store to buy more the last night of our trip so we could make it home since Disney only sells Carnation (we tried Carnation that ended up being a no go).
We never went back to the room for naps when they were that young. My kids always napped in the stroller. We would use that time to ride the attractions they couldn't ride (especially when we only had one kid). One afternoon, we each rode Expedition Everest about 5 time each using the single rider line. We would also tend to save Rider switch tickets and use those during nap time.
We always bring the table topper plastic disposable mats and baby food to each meal when dining at that age. We were just starting to introduce some table food.
Biggest thing is to go with the flow. My oldest ended up being really afraid of characters and fireworks at 10 months. By her next trip, she wasn't afraid of either. Once we figured that out, we skipped all the rest of the night shows that trip and avoided characters.