TITLE: References request on the algebraic geometry of projective homogeneous spaces
QUESTION [9 upvotes]: Hi everybody.
Let $G/P$ be a complex projective homogeneous variety with $G$ a simple Lie group and $P$ a parabolic subgroup.
I believe that it is possible to 

(1) describe ${\rm Pic}(G/P)$
(2) characterize the ample line bundles and 
(3) express the canonical class of $G/P$ 

in terms of the nodes corresponding to P in the Dynkin diagram of $G$.
Are there some canonical (or a least some good) references where this is explained?
This is certainly "well-known by the experts" but I'm not one of them... 
Thanks to those who will answer.

REPLY [2 votes]: In addition to the references already mentioned, let me recommend Dennis Snow's excellent notes on homogeneous vector bundles. They cover everything you ask for (and much more):

For a description of ${\rm Pic}(G/P)$ in terms of weights, see Theorem 6.4.
Ample line bundles are characterized in Theorem 6.5.2.
The canonical class is described on page 37, right above Definition 10.2.