I think it needs to be said that the kinds of clothes you wear will be the first thing any guy notices about you. That being said, fashionable clothes can mean different things. Things like uggs or skinny jeans are very fashionable, but I don't like them all that much myself. And further more, simple "normal" clothes can look every bit as sexy as "fashionable" clothes when they fit well. But for me what it boils down to is that you should wear the clothes you feel most comfortable in, because if you're comfy you're confident, and confidence is hot.
Style is really only a small part of it for me. As long as the girl is wearing clean clothes and actually looks halfway decent, she has just as much a chance as any other girl. Granted if by fashionable you also mean really flashy, then that one will of course seem to get more looks of interest but if those looks are good or not, really would depend on the guy himself.
Style, yeah, in fashion, not so much. I'm actually more apt to pick a lady wearing generic clothes that look nice, than I am to pick some woman who is plastered in logos and brand name clothing. There is nothing wrong with wanting to look nice, but it's a bit ridiculous to me to pay so much for something you can get for much less. Most the reasons to do so just aren't what I go for.
Well, I can't really provide you with a decisive answer for that one because are other factors involved. Its not really that black and white. However, I know that I find it attractive when a girl wears fashionable clothes. Not a label whore, but a girl that has a really 'cool' sense of style and is presentable and sophisticated.
I would look at both girls just the same our first impressions is made by a girls style however the impression that last is the way you act and your personality. Personally personality is more important to me than anything else in a girl