1. Can you tell by reading a paragraph if a man or woman is the author?
Generally - no. Still there were some instances when I read a message and I find myself thinking: "This has to be a girl!" (no offence)
2. Do you find yourself looking for the use of similar words in each message you read?
No, but if someone is using repeatedly a word/expression I usually notice it.
3. Do metaphors turn you off or would you rather the author be more descriptive rather than trying to use something modern to describe something old?
It really depends on the case. Usually I prefer a good description, but sometimes a well-used metaphor could be priceless.
just for the Q1:Can you tell by reading a paragraph if a man or woman is the author?
The difference between men and women results in the difference between both writing styles. women tend to express their opinions more personally or more or less related to herself experience while men seem eager to let readers know what he's skilled at quite well,especially when using the metaphors or so. but there's an admitted fact that most women writers relied on her autobiography or autobiographic magnum to aquire fame, such as Elfriede Jelinek who's just won the Nobel Prize for Literature in 2004 and Syliva Plath with her book
also, it may depends on the language that the author employ during his writing process. English might not be the language to show the distinctive styles adopted between men and women. I think Chinese can show much subtle difference in this aspect.