·Lore of DoW is the whole Wh40k universe...It requires at least 1-2 years to read all of them
·In DoW1 and all of its expansion there are 9 factions, Space Marines, Imperial Guards, Sister of Battles(Adeptus Sororitas), Orks, Eldar, Dark Eldar, Necron, Tau and Chaos
In DoW2 there are 6 factions to play(SM, IG, ED, Orks, Chaos and Tryannids) in PVP and 8 in PVE (with Tau and Necron)
In DoW3 there will be 3 as starting factions but I guess there will be more in DLC
·Melee is as important as shooting in DOW and Wh40 universe
·These 2 are Knight-Class Titan of Imperium and Wraithknight of Eldar in trailer.
·COH1 used improved engine of DOW2, they are very alike. DoW1 is another game.
·DoW2 is more of micro-control game, but 80 apm is enough
For more background information, you can visit
http://wh40k.lexicanum.com/