>>1507
>I heared some of his posthumously published works got changed, anything I should avoid?
No. The posthumous stuff is edited by his son. You can say a lot of things about Christopher Tolkien, but he has profound respect for his father's work. Anything where he's the editor, you can't go wrong.
Silmarillion, Beren and Lúthien. Children of Húrin are all top. Definitely recommend them.
Also recommend the 10th volume of History of Middle-Earth, called Morgoth's Ring. It is perhaps the most important academic work about the theological aspects of Tolkien's world.