For 1): Chapters 4-6 (this is a single bound text) of Bourbaki's Lie Groups and Lie Algebras is often said to be the most comprehensive introductory treatment on root systems. Much modern work in linear algebraic groups and related finite group theory makes reference to it.
(In fact I have heard it said that this is the high point of the entire Elements of Mathematics series, though this is obviously a matter of taste. For my part, I believe I currently like Commutative Algebra the best.)
For 2): apparently yes. See e.g.