1. There are slightly fewer women than men into the heavier end of music, but not big enough to make a difference in my opinion.
You would've done so well, if only you hadn't included this point. There are FAR less women playing heavier music then men (except for maybe punk, ok tommy?

)
This has inspired me to do some more genre specific searching. (
http://www.last.fm/tag/genrename/artists is the way I'm doing it)
Top 50 metal bands (some of which aren't metal, but anyway): SIX females. Actually as much (per capita) as the last.fm top 100, but still NOT A LOT. And Evanescence isn't exactly metal.
Top 50 punk bands. Now, punk is pretty subjective but so is metal- there's certainly a few stinkers in this top 50 that clearly aren't punk (blink 182, anyone?). Anyway: ONE. At least I think so (black flag bassist was female?), there may be a few female bassists/guitarists/drummers I don't know about. Definitely no vocalists, though.
The two traditionally 'heavy' genres out of the way, (and me having proven the over guy wrong). I thought I'd look through some more genres.
Top 50 indie bands. This could be quite interesting (i know this is a subjective/meaningless genre etc etc). Thirteen here. Less then i thought, actually. I may be out by two or three, I know all the bands there but only vaguely.
Top 50 Rock bands. Again a bit subjective. The Evanescence singer, Meg from the White Stripes and Kim from the Pixies (I hope her name is kim.. isn't there a Kim in Sonic Youth? Maybe?) prevent it from being a clean sweep.
Top 50 Pop bands. Could be interesting. 37 women! Quite impressive. 7 out of the top 10 are women.
Top 50 BANANA bands. Only Gwen Stefani gets in this illustrious tag. There aren't 50 bands, though.

Top 50 Jazz bands. I'm just going off singers for this one. (And there's NO WAY that Norah Jones or freakin' Michael Buble is jazz, ffs.) Anyway, eight of them, most them up in the top 20, though.
I'd like to do the top 50 twee bands, but I have no idea who any of the bands are and I can't really be arsed looking through all of 'em. Perhaps someone else could do this?
Anyway I'd do more but except for drone (7 girls in the top 50, I think) I don't really know any off any other genres well enough. That concludes my little survey thing, I may be out by one or two in a few places. I know I didn't count the guys but for, say, Metal and Punk, there may be over 150 of them in each genre, and I can't be bothered doing that.
Interesting to note, as well, the sausage fest that is Death Metal has TWO (Bolt Thrower's Bassist, Arch Enemy's Singer) females. Come on punk, pick up your act
