Female Vs Male Speech.

I could imagine that this question could be quite difficult as there are quite a few examples of stuff a woman simply wouldn't say and stuff that a man simply wouldn't say. I have been studying Japanese at school for nearly three years now, and it's only recently that I have started talking to real Japanese people, other than my teacher who is actually a Korean.

So I recently discovered the penpaling part of this website and have quite a few good penpals. Problem is they're all female. I'd rather speak to females, as they tend to be more chatty than their male counterparts. Plus the fact that they're females and I am a male. I have one friend who I speak to on MSN regularly basically for a few hours every day and I always talk Japanese to her, and she always talks Japanese to me. Through my own discovery I have learnt that there is a lot of strictly female and male speech. I have learnt a whole lot of Japanese from this girl, but I'm wondering if most of it would be feminine language.

So are there any major differences between masculine and feminine language? If there are how could I tell? Any general rules? I'd hate to talk to go to Japan and talk to males like a 16 year old girl would.

I wonder in what kind of "tone" you are talking in.... I am sure that your penpal herself would say something if you spoke like a girl (provided she knows you are a guy).

Just to list a few examples, for one thing, sentence ending would differ distinctly: ...wa for females, and ....ze would be a typical male (masculine tone) sentence ending. "...yo" and "...ne" might be neutral.
The pronoun "I" would be distinctly different too - "watashi" is a neutral one (the preferred pronoun in polite speech at all times), "atashi" only by females, "boku" (by boys to young-at-heart), and "ore" (quite masculine) by males.

One male student I used to teach Japanese to was made fun of by the Japanese friends he made, because he allegedly talked in a soft tone like a woman. Well, yes, the teacher was a woman so he picked up things well ;). But eventually as he came to stay in Japan and met with many people, his speech settled into something that sounded natural to him.

My penpal was talking to me about nicknames and basically told her I don't really have one. But she said that she is known as うめちゃん, so I call her that whenever I speak to her. Whenever I address her as this she always calls me やほ. Does this actually mean anything or is it just a word she has made up for me?

"Yaho" or "yahho!" is like "Hi!," a very casual greeting, it's not referring to you :)

Damn all these colloquialisms that don't come up in dictionaries.