I just watch the TV 显示 when I can, but I've read the 图书 and I know that they're super different. Relatively what book are they at in the TV show? Have they figured out who the first A is?

The A's are different in the 显示 and 你 do not know who A is 由 the end of season 1. As for what book they are up to 由 the end of the 10th episode they have finished book three and from there they are moving in their own direction. Some things are the same such as Ian's body disappearing but they have also introduced characters that are not in the books.
Hope this helps