Nine months is such a easy and fun stage!
Sleeping-Try to keep it as close to home as possible. Co-sleep, regular crib (you can rent), or pack and play if he has slept in one before and does well.
Bring his sheets or at least a blanket from home and any sleep toy he might use. Pack both cool and warm PJ to allow for room temp adjustments.
Bottles- I am a huge fan of the expensive single feeding bottles IF the nipples are like what you are use to and you can find your brand in them. Otherwise...stick with what you have. Powder is the easiest if he likes that. Take enough for each day and a bottle brush and soap to wash at night. October may still be quite warm so you may wish to offer extra water, or diluted juice if your dr is ok with that. A sippy cup introduced a couple months before the trip would be nice too.
Food- Number ONE rule is to not introduce anything new on the trip. Our little guy has food allergies and we have lots of experience with them. A first reaction can occur with any kid, any time. The pouches are great and there is an active post on flying with them. Tastes of foods that he has been exposed to before off your plate are great. You can find yogurt, apple sauce, etc most places too. Take disposable bibs and place mats. Finger Foods are a life savor and can allow you to EAT dinner....but only if your little one is ready for them and try each at home first.
Stroller- Be sure that you have a good reclining one with a nice share cover and snack tray. A carrier is also a great idea. Be sure to use it a lot before the trip not only to adjust him to it, but also adjust you to the extra weight.
Diapering- Disposable pads and plenty of diaper rash cream, just in case.
Sun Screen- Cover as much skin as it is cool enough to do so and use a good infant brand...I like neurtagena for babies. Add a wide brim hat if he will wear it.
Bring his normal bath/hygene stuff, extra passy if you use them, a few toys and books, and maybe a quilt for tummy time on the floor of the room.
Do the things that YOU want to do. He will be thrilled to be with his parents and see and smell and hear all the new sounds and will be just as happy to be in Space Ship Earth as Little Mermaid. Unless he reacts to loud noises or dark, he is too little to be afraid of things like the HM or the Great Movie Ride. Have fun!!!