To be honest, that sounds a lot like the Eldar. Small numbers, greater skill and specialization, limited territory.
I agree with most of your post with the exception of one faction. The Orks should be able to take a beating as well. Base Orks should be tougher than Eldar, and once you get more size/status and "armor"/sheetmetal, Orks should be on par with or greater than standard SMs.
The dude above you was being sarcastic :/. Also, I don't think SMs would steam roll even the CSMs+Tyranids let alone F2Zerg Orks and Eldar.
I don't think so, on the tabletop they may be similar in toughness but their armour is lacking, making them obviously far weaker than SM. And fluffwise they're no match for astartes, and they only win via 'green tide'. So they should be somewhere between Eldar and Astartes. However Orks players who have paid should be able to play as Nobs which should indeed be similar toughness to SM in the game.
The nobs, even minor ones, were what I was referencing with the increase in size/status portion of mah post.
If it ends like this: http://1d4chan.org/wiki/Dawn_of_Eldar We will still call it "Stupid Mon´Keigh Propaganda =)) Solved