A few questions about the USA

Hi, I am looking at moving to Chicago with my husbands work. We have 3 kids and I have a lot of concerns about the US. First I grew up in Canada so cold winters, flat land, everything miles apart doesn't worry me what does is as follows: School fees - I understand in the USA there are fees for books etc. which can be expensive. what do you have to pay for? is it just books? how much averagely or worst case scenario is it? Jabs - I looked up the American immunisation schedule and see that kids have jabs nearly every month when little and many until 12ish. I am very happy to follow the British immunisation schedule but the US one seems over the top. opinions on it ys to avoid the strict schedule appreciated. Health Care - My husband will have some covered by work and we pay a premium I believe... does that cover the whole family or just him? How much does a decent care package for a family of 5 cost and which is a good company to go through? Blue cross etc? Tax - so Americans have to pay tax even if they have never lived in the USA, we want to live there but eventually go to Canada... will we have to pay tax when we leave? I am confused by what I have found it seems that if we live there for 3-4 years we will be liable for tax forever or have to pay to no longer pay tax!!!! One minute I am excited to be in North America again the next I am terrified. Any words of warning or encouragement would be great. What is good about living there? (please don't say weather, I already know that one) What makes living in the USA a good idea? Why is it better than the UK? Thank you for all help