Hi! I'm a woman who plays magic and falls into the very small percentage of female magic players who actually attend large-scale tournaments.
1) I don't know if women are more sensitive to hygiene (not having ever experienced the male side), but I do know that women, as a whole, tend to be a little more concerned with public perception, at least in part because women are unconsciously brought up to believe that their worth stems at least in part from their looks, and their intelligence plays a much smaller part than their male counterparts*. One person remembering to shower instead of stink is probably not going to do much, but the community as a whole not embodying the nasty nerd stereotype so much would probably do a lot to bring more women in.
2) I would say that 95% of people at your average 1500-3000 person tournament are hygienic, friendly, and socially conscious. Maybe the average Magic player is a little more awkward than the average person you'll meet on the street, but that doesn't matter so much. However, it doesn't take that many smelly assholes to poison the perception of a group as a whole, and the average number of Magic players who don't understand the concept of showering is, well, enough higher than the average number of people you'll meet on the street who don't. I usually end up within smelling distance of someone who clearly has major hygiene issues around once or twice per large event. When you consider that there are thousands of people at these and they last 2-3 days it doesn't seem that bad, but the fact that it's pretty much guaranteed you'll encounter one doesn't say good things for the community.
This may be a somewhat controversial idea. I'll just say this: obviously *everyone is judged based on appearance, but think about how many "ugly" male celebrities you can name off the top of your head (I thought for four minutes and came up with nine), and then think about how many "ugly" female celebrities you can name (I can think of two...).