On our first trip, DD was 5 and my niece was 1. Travelers were me, DH, DD, my sis, bil, and niece, we were there in early March, stayed offsite, and we had a car. I had read some of the Unofficial Guide to Disney World (still my favorite and what I'd recommend first) and came up with some basic park strategies, mostly for MK. I tried to get the layout of the park straight in my brain, decide which attractions we could eliminate, and then read over the suggestions and touring plans. We didn't do any of the evening parades or fireworks, and we didn't park hop. We tried to get to the parks fairly early in the morning (maybe not rope drop, but close), stayed for lunch and the afternoon (luckily the girls would nap in the strollers), then headed back to our condo around 6pm. We either did take-out supper (for example, call Olive Garden as we left the park, by the time we got there the order would be ready) or my sister and I dropped the husbands and girls at the condo. They'd get supper ready for the kids (chicken tenders, mac and cheese, etc.) while my sister and I went to Goodings and picked out ready-made individual meals for the adults. We'd heat our supper while the kids were getting ready for bed. It worked out well, as it kept the girls pretty close to their usual sleep schedule (which in subsequent trips we abandoned, but we could do that with our kids) and kept the parents pretty well rested, too.
One thing we learned was we all travel better if we do 2 park days and then a down-day. Sleep in late, play in the pool, go to Downtown Disney, etc. IIRC (it's been a few years, like 17?), we spent lots of time meeting characters on that first trip, so remember that you can't stick to a religious time schedule and still meet characters. I believe we did one in-park breakfast at Crystal Palace, so the kids (and the adults!) could meet Pooh and the Guys. IF you can afford the buffets (and the prices have skyrocketed in the past 15 years), a character buffet is a good use of time. I've found most meet and greets will take about 30 minutes. If you do 2, that's an hour, and then you'd still need to take an hour to eat lunch. If you can afford a character meal, it's like doing double duty, eating while doing a M&G. HOWEVER... there is no real need to do a character meal, if you are happy to relax and go with the flow. Also, remember that many kids are frightened of the fur characters (the ones in full costume, unlike princesses/princes, where you can see their real faces... aka, face characters). It sounds like you'll be in a timeshare, so I'll guess that you'll have a kitchen. I'd plan on having simple breakfasts at home, that you can eat before leaving, or even in the car on the way to a park. We find that mini-bagels, yogurt, cereal, fruit, etc. work well.
For my family on a 7 day trip, I'd get 5 day base tickets. You can do 2 park days, a down day, 2 park days, a down day, and a park day. Start and end with MK, then do one day each at Epcot, the Studios, and Animal Kingdom. IF you find that you need more time in the parks, you can add hopping once you get there... so if you had a short day at the Studios, you could hop over to MK for the late afternoon/early evening. REMEMBER that you will be walking about 8 miles a day in unbelievable heat, so DON"T over schedule ourself!
Plan around your kid's usual schedule. You know him best. With our girls, we learned that too many qs/ts meals would wear on their systems, so we were careful about what foods they ate, and made sure to get a decent breakfast in the morning. We had stroller-sleepers, so we could stay in the parks through the afternoons, but when they were little they really needed to be in bed between 9 and 10 (and that was stretching it). After all our trips (DD and I are planning #26? #27? for November), I think the most important thing I can pass on is to remember to keep people's sleep and meal needs in mind. If everyone is well-rested and appropriately fed, you'll have a better time overall. I can pretty much promise you, this won't be a "once-in-a-lifetime" trip; it'll be the first trip, with more to come!