I didn't say that a woman couldn't be a hunter, I said it seems more suited to men. I know there are women who do fine on their own, but also the physical side, and no I am not saying that women are useless at fighting and physical stuff, just tha men do tend to be stronger and over time I feel the physical effects of continually being beaten up would affect a woman more than a man.
Also, even if there was a woman hunter in Supernatural, apart from Gwen, how woold that fit into the story. TO make them a regular would be difficult because Sam and Dean do tend to hunt alone, although I did like it when they hunted with Ellen and Jo, but what would be the reason for them to keep meeting up with her. I feel the major problem with having a female recurring character is how would she fit into the story. If they found a perfect way of doing that then that would be good, but I just do not see how.
As to Cas being a frmale angel, I do not feel you aould have got the bond with Dean as it appeared to me that Dean was almost like a big brother teaching a lttle brother how to be a man and have fun. I feel that there would have been an awarkdness between them which would have been a bar to them becoming friends. Part of the reason Dean bonded with Cas so well seems to have been that as Sam was drifting away from him and towards Ruby, Dean seemed at times to see Cas as a substituate brother.