I really dont understand this Q!

For part i) I got an answer of 0.535645, however the answer in the back of the book is 0.535644??

For part ii) i got 1 + 5x^2 + 10x^4 + 10x^6 + 5x^8 + x^10 , im pretty sure thats right however for the next bit i got an answer of 0.5826, but the actual answer is 0.527147??

I do not understand iii) and iv) at all, please help!

Thank you so much