whats going on with COH games on steam?

what happens to the game Company of Heroes?
what is the difference between each version?
Company of Heroes
Company of Heroes - New Steam Version
Company of Heroes - Legacy Edition
which of the games is worth buying to play multiplayer?

what happens to the cards for these games, are there currently three types of cards on the marketplace for the same game? (this is without taking into account the cards for the second part of the game)
Which of these cards are no longer available for drop, and which of them will drop out when buying a game?

why did I lose some of the cards from the game Company of Heroes from my inventory and was replaced by Company of Heroes - Legacy Edition? these are different cards with different cost
(I ll understood if the cards were simply renamed, but no, I now have some of those and some others)

there is madness on each forum of game, i cant find answer anywhere, maybe u know some information ?