My advice is always to rent a car. I know many are happy with Disney transportation, but we love having a car. We are DVC members, so we often stay at BWV, including our first stay with our DS when he was only 8.5 mos (he's now 25 mos). We had a nice trip at 8.5 mos and our DS did great. I would recommend requesting a crib from the resort if you haven't done so. To our surprise, DS would NOT sleep in the pack and plays found in the BWV rooms. You may want to bring a few blankets, especially something for your granddaughter to crawl on the floor on.
As far as a true list, it could be endless at that age! I know I brought WAY too much stuff for DS at that time. However, maybe a few of these items will be helpful to you: nice sun hats, favorite toys, books for bedtime, disposable spoons and bibs are great for dining out, a few standard bibs for eating in the room, favorite videos (if she watches any--plus my BEST advice for flying with young children is a portable DVD player for the plane, even at 7 mos), blankets are also handy for draping over the stroller if you granddaughter takes a nap in her stroller plus the sun can be so bright it is nice to block it if you can, her favorite lovey, swim diapers if you plan on going to the pool, baby-friendly sunscreen, misc. baby meds such as gas drops, baby tylenol, ambusol for teething, just in case, nursery water (to make bottles), we have found that a stroller fan is very very helpful (found ours on ebay),
We also really like having our rental car because we need so many things when travelling with our little one that we like the freedom to run to the store and get diapers, nursery water, diapers, or whatever is needed, versus paying the exorbinant Disney prices. I'm sure I'm missing alot but that was all I could think of right now. Good luck and have a great trip!