Can you share some of the actually details on the changes you made?
Our family has been working through this book for over a year now and so I can't even remember all the changes we've made! But I can respond to some of the things you mention:
First, I LOVE having regular meal days. We made a little menu board that says "Monday: Italian" and then has a space for the specific meal. "Tuesday: soup ______" etc. It's really simplified things! For your 4 year old you could even have a picture of it, if you feel like you want him to understand/know the rotation.
For screentime, I am with you about being confused! We do use limits in our family, but they're not super clearly laid out. In my head I have this thought that I don't want tv-watching (or computer usage) to be a daily thing). Our eldest rarely watches tv during the week, but the middle one watches every day while I put the toddler down for her nap. It's something I'd love to change but don't know how right now. For us, it's only a problem if it's interfering with active play, friends, and solo play. There needs to be enough time for all of those, screentime is lower on the list for us.
Books - we have a few books (usually about 5) for each child at the spot where we do each child's bedtime. Those books rotate, sometimes because a child will bring a different book up and the shelf/basket gets full, or sometimes because I actually go in and rotate them. We also have bookshelves - one in the family room, one in the dining room, and my daughter has one in her room. They rarely use the shelves and instead just read the books that are in the smaller piles. We also have a small shelf with library books, which I make a point to pull out on a regular basis. We also pulled out all books that are seasonal. Those are now stored in the basement and only come out during the appropriate season. Currently we have those under the xmas tree, though I'm thinking that for the next season they'll just be in a basket in the living room.
Toys - I LOVE rotating toys! First, I'm always putting toys away in the basement. The kids know they can get them anytime, but they very rarely ask. Then whenever they start to feel a little more bored, or seem kind of played out with their toys (every few weeks for the little one, less often for the bigger kids) I just go down their and pull out a bunch of new ones. That way, we only have one or two building sets out at a time, and I can also reduce the number of toys with lots of pieces. The system isn't failproof but I do really love having fewer toys in the main living areas. It's a lot less clutter and quite quick to clean up.
Previewing - on Sunday night I pull out our planner at dinner and we talk about the week. We also preview the next day with the kids as we tuck them in. During times that are very different than their regular routine (like school breaks), we actually have a little set of index cards with the words and a picture of activities we generally do. I then post those on a felt board each night so when they wake up they know exactly what the plan is: "breakfast and get ready; playground; lunch and rest hour; arts and crafts; relax and play; dinner and bedtime" for example. They really enjoy this and when I get my act together I'm going to start doing it with the two kids who are still home with me most of the time.
For a few other rhythms and routines that we do, we have family fun day one Saturday a month. During it we go to the local breakfast joint and then do something that we've all agreed upon during the week prior. On Saturdays we also (usually) do chores all together, we go to church on Sunday and the older two talk with their birth parents on the weekend as well. We eat dinner together, have snack together after school (which I really had to make a point to sit down for, it's been great!), and have reduced breakfast choices to "whatever mom makes, or cereal." I really loved the section on rhythm :)
That's all I can think of for now, does this help at all?