So many of your questions are things that people will have varying opinions on. A lot will depend on what your interests are as a family and things like what your normal routine is with naps and bedtime at home. Most people will probably recommend that you stay somewhat close to your kids regular schedule, so if they're up early and in bed early, hitting rope drop and skipping the night shows might work best. For my family, my toddler sleeps until like 11am and goes to bed between 9 and 10. My 7yo gets up by 830 for school but is able to be more flexible. Rope drop would have been terrible for us. We woke the kids up around 930-10 and then headed to the parks, then stayed until close. Go with your gut on that, but don't be afraid to tweak things when you get there based on how the kids are handling it all.
Strollers- Are you staying on site? Will you have a car or are you taking the Disney buses? If you rent strollers at Disney, you can't take them out of the park and you are probably going to want them for the trek to the car or while waiting for the bus, so I would being your own or rent from an off-site vendor. If you will be using the buses, remember that strollers will need to be collapsed before you get on. It's not a huge deal, but given that you have 3 small kids and presumably only 2 adults, I would bring/rent off-site a double stroller. The kids can take turns riding, but then you only have 1 stroller to deal with on the buses. One adult can handle the stroller and the other can wrangle the kids.
Rides- How tall will the kids be and if tall enough, would they want to ride some of the bigger rides? Google the height requirements and look at the info for each ride. Some kids get scared on certain small rides with no height req (like Haunted Mansion and Pirates), but others preschoolers find them lame and would rather go on things like Big Thunder and Soarin. My toddler loved everything he was tall enough to ride on. You know your kids best. For rides that not everyone is tall enough for, you can use rider swap so one parent can stay back with the too short kid(s) and get a rider swap pass to ride later by going through the fastpass line (so you don't have to wait as long).
Restaurants- Since you have the dining plan, I would recommend hitting up some character meals as then you won't need to wait in line in the parks to meet them. You can take a break, enjoy a meal, and meet some characters all at once. These also tend to be higher priced meals, so they are a great value on the
DDP. At buffets and family-style restaurants, the 2 yo can eat free, so that's a bonus too. Some of our favorites with kids are Garden Grill (Mickey, Pluto, Chip, Dale), Crystal Palace (Pooh, Tigger, Piglet, Eeyore), CRT (Cinderella + usually 4 other princesses- 2 dining credits), Bon Voyage (Rapunzel, Flynn, Ariel, Eric), and Tusker House (Mickey, Donald, Daisy, and Goofy). Buffets can be a little difficult sometimes with kids because of having to take turns to get food, carry multiple plates, etc, but it is doable. Look at the menus for restaurants and see what might interest you.
Don't try to plan every second of your trip out as with kids, you never know when something might come up and you need an unplanned break or snack, or the kids want to ride the dinosaurs 8 times in a row and there's no line. Come up with a rough idea of what park(s) each day and schedule your ADRs and fastpasses. I personally wouldn't try to plan down to the minute like 9am rope drop, 905-935 Pirates, 935-940 walk to Flying Carpets, 940-950 ride Carpets, 950-1005 walk to HM.... Some people like structure like that, but as I said, with kids things often take longer than expected and you don't want to stress yourself out trying to stick to a strict plan and being afraid you'll miss something.
Take a deep breath, relax, and you will have a great trip.
