Female. Gotta love a badass girl with a big gun, and even more so a badass girl that could kill you with her brain.
Correct. Though I can live with having a main in which I don't deviate Aspect and a floating second toon which goes any of the classes as needed. So my main will be a male Striking Scorpion and my floating toon will be a female AnyOfTheOthers.
Both and none. I don't think I'll refrain from playing space marines just because Eldar are there. Besides. Ork's might be fun. But what gender of eldar? Female. Most likely.
Female. I almost always play female characters when I'm given the choice. Lore-wise, female Eldar who become Striking Scorpions, Dark Reapers or other male-only Aspect Warriors, bind their chests so they appear male when wearing their armor. Likewise, male Eldar who become Howling Banshees stuff their chests and tuck their junk away to appear female when wearing armor. Eternal Crusade is deviating from the lore to make it so that female Eldar always appear female and male Eldar always appear male, regardless of which Aspect they choose. Which is totally fine with me.
I actually would have preferred the Aspects cross-dressing to match the Aspect which they portray. It goes with the idea of wearing the masque of your Aspect, to don armor / form which mimics that Aspects appearance.