Not really. Idea behind this is that you are competing in a market with far less competition. Its the same idea as being a hot gamer girl. You're appealing to a niche rather than just another hot girl dropping her pants. Its an easier market to attach yourself onto. Show some actual effort in your cosplays, while being attractive.
Sure, but I mean you don't have to go through the effort of actually trying to get the costume right. If your objective is to get nerds hot and bothered, all you need is the illusion that you're 'one of them'. You can half-ass it with something that isn't accurate but panders like hell. Again, it's probably easier to get a white halter top/hotpants, add a cape cape and do 'slutty powergirl' than sewing every part of the costume to match the design, as baroness said.