Draenei shouldn't even be there at all. Warcraft 1 and 2 both described (in the lore described in the manual) how the Draenei were slaughtered to a man, without much difficulty by the Horde. And then, suddenly, they are a super-advanced race, that managed to fight their way from Draenei, causing heavy losses? Bollocks. It pissed me off to no end when I heard about their inclusion and the "lore-retcon" that was the expansion "Burning Crusade". I feel that it is at that point that WoW came of the "lore-wheels". It caused quite an uproar by "lore-purists". Chris Metzen (Head Writing Department) even issued a statement, saying he messed up with the Draenei. So, if you are going by "pre-WoW" as a basis, drop the Draenei. At least, I would do so.
The apology was in regards to the fact that the Warcraft 3 manual states that Sargeras was corrupted by his personal war with the burning legion, and specifically by the eradar, while BC's background for the Draenei says that they left their homeworld when Sargeras came to their homeworld to turn the eradar into demons.
Broken Draenei were included in Warcraft 3's expansion, and were, I think, shown to be quite stealthy after having to hide from orcs all the time. I didn't play it much myself though, so I'm not sure. My brother beat all the campaigns, and I remember seeing that. Personally though, I'd only include the broken draenei, and I wouldn't make them playable. But that's because I'm not entirely sure how some draenei remained unbroken, and also because they arrive in a space ship when everybody else from Draenor has to go through a portal.
If you do this, be sure to include as many ores and plants as you can. You may have to come up with some special underground crops(all I can think of right now are ghost mushrooms and the lichen from BC), but there's a lot of fun surface plants that you can give to different biomes. Like Grom's Blood requiring a savage evil biome.
I wouldn't worry too much about playable races, but probably orcs and humans should be the starting point(also, Scourge were playable in WC3, though that would be more fun if you end up being able to do necromancy in fortress mode). What I think you should work on more is populating the world with the creatures of WoW, and deciding if you want an amalgamation of everything on one continent or if you want to force the game to focus on the eastern kingdoms. I'd personally say that everything should be in, and the game will be a random Azeroth generator. Though I guess that means that quilboars and gnolls could end up sharing territory, since the both kind of live in open fields.
Maybe I'm underestimating how much you have to do in making a race playable though. While it really only requires making the proper noble positions and possibly ethics in this case, you probably want to include all the proper clothes and equipment as well, and that takes time.