I totally agree with everything that has been said- allearsnet.com, tourguidemike.com, disboards.com are my go-to resources. We do the 2 meal a day plan- one sit down and one counter service plus two snacks. We still book character meals and love them. Plus, we take a "10 minute" drink and snack break every two hours: we found this works best with the kids and the husbands. There are so many food choices at Disney it is hard to know where to begin. Allearsnet.com has copies and prices for all the menus. Because the quality of food can vary, and my husband has to be fed or he is a grump, I always check the restaurant reviews at the disboards. Make meal reservations as soon as possible. You can always cancel them, but you can't always get them.
I also use a travel agent (free, from cruising co. to book my meals, make sure I have the best prices- she tracks the hotel codes, packages, etc. so that if better prices come up, I get them) who is phenomenal about tracking everything for me.
I use tourguidemike's information as the foundation to plan around: one word of warning, however, some of his sample tour plans are a bit out of date, so you have to search through his site for the most up-to-date information. His recommended days of the week are always right on, no matter when you go. He also walks you through fast passes, the reasoning behind his method etc.
I skim the Unofficial Guide to Disney for some of their plans and information, but a lot of times I don't agree with their reviews. They also have a touringguide website where you pay about $12-13 per year and can print out maps and itineraries for the day. I like to combine these and tourguidemike's sample plans plus our "insider" (going to the park 23 times since Michael was born) information to plan our days.
What time of year: definitely I would not go in July or August- crowds and heat. Other than that, there are pros and cons to the rest of the year. Check the events listed at allearsnet.com and the crowd levels throughout the year at tourguidemike and in the Unofficial Guide.
Things for the husband: My husband hates crowds, so we always "go early, leave early, nap, and return in the evening for a good meal and fun activities." One thing I planned for him to do that he loved was the racetrack- drive a racing car, etc. I forget the name- Richard Petty, maybe. It cost extra but it was worth every penny because he enjoyed it. Also, we go about every other year for Star Wars weekend, and it can be crowded, but my husband loves it. He also loves Animal Kingdom Lodge, the special Christmas programs, and the Halloween parties.
Although you do get better accommodations for your money when you stay off-site (much better in terms of room size- the rooms at Disney are small by comparison), we do stay on-site for the convenience (we don't use the extra magic hours) and choosing which resort to stay in is difficult: do you want to be on the monorail near the Magic Kingdom so you don't have to deal with the buses as much (this is assuming you will be spending a lot of time at MK) or do you want to get away from the parks (Animal Kingdom Lodge is wonderful- we stay for part of our trip every time, but the bus ride to the MK is 20 minutes or more)? If you are going for budget, all of the All Stars and Pop Century have something to recommend them. It is a matter of taste. Pop Century seems a bit more cohesive, but we have enjoyed them all.
We have taken my son since he was 4 months old. And, yes, he doesn't remember a lot from his early trips, but they were great fun, and he had a blast. So, I am a bit torn as to what age is best. I agree that if this trip is going to be the only one for a while, I would wait until he was 6 to 9 years - Michael definitely remembers those trips.
Our trips have changed over the years- the focus, activities, and pace. When Michael was younger, he liked the characters and the playgrounds as well as he liked the rides. The talking trash can, the fire hydrant that squirted water, and the talking tree were especially thrilling to him at your child's age. Looking for hidden Mickeys and collecting pins have always been popular.
We rented a stroller until our son and his cousins were 10 and 11. It was so worth it!!! Kids get tired and grumpy no matter what their age when it is hot, etc.
If you have any questions, you can shoot me PM- we were there in June and plan to go sometime this summer/fall (depends on when we go to Spain).