That's great advice to have a newborn footcare kit! It's great to make them feel productive and needed!
I have six children and now #7
on the way. One of the most important things was making the older ones feel like they were part of the whole event. They felt like the baby was theirs too!
I found that continuing to snuggle, read to and have a little alone time with the older ones when possible made them feel much more at ease. I tandem nursed through three of my pregnancies and that really helped. One of my favorite memories, was nursing my toddler with the new baby and the toddler gently enveloped the baby's head with his small hand. He then said, "I'm teaching the baby to nurse." It was magic.
Another really helpful technique is to have the older child buy a present for the baby, then receive presents "from the baby." once the baby was born. This really excited my children and made them feel important, included and loved. I think that never making a correction "because of the baby" is essential. If they are moving too fast I always tell them that I am worried about them bumping into me, not the baby. Really, really important. It avoids most of the resentment that I think comes between siblings.
Wearing your new baby is a great tip too! I wore my sixth on my back when he was very small in a woven wrap. My arms were free for the others during that time and he loved sleeping like this. I also wore him in a ring sling.
Only once did we have an issue. My fourth son felt a little displaced. He eventually said, "I want him (the baby) to go back to his 'friends'" meaning of course wherever he came from before, lol. He was quite serious and concerned. I said, "We are his friends. He only has us to take care of him." My fourth son's eyes widened. He looked compassionately at his little brother and ran to get a toy to give to him and stroked his head, saying that he loved him. He would take care of him. It melted my heart. I tried to make sure my fourth son got some good extra attention to help with his feelings.
I will say that regardless of all these positive measures and interactions, my kids do still have conflict. There is no way to avoid it entirely, but each disagreement is an opportunity for learning and maturing.
You are all going to be fantastic with two. I found three to really blow things out of the water and then after that it was more of the same, LOL!