B.) It's very true to the original, I could follow the text in my head and match it to the screen. Conversely, there are numerous additions, expansions, and some omissions to the text. For the purists among us, rejoice. You will have plenty of material to gripe and kvetch about for weeks on these and other boards. There will be plenty of opportunity for you to show how smart you are in your maticulous knowledge of C.S. Lewis. Don't pretend you don't like it.
Most changes seem to be of the cinemagraphic kind, the make the movie flow well or increase drama. Lewis' text is very realistic, with events happening over time. These gaps are usually eliminated for the movie. Other events are rearranged or added to give more drama and emotional tension. The beaver's house is fled while the wolves attack, there is an icy river action scene, etc. These scenes seem fine for what they are.
There are many little omissions. There is no stone knife, no scene of the witch hiding as a boulder, Rumblebuffin in not introduced properly nor does he knock down the gates, Aslan doesn't play with the girls, and I do miss the scene of the animals celebrating Christmas. Which brings me to my next point.