Regarding the Sheik gender argument-- There really isn't a "true" correct answer. The way I see it, there are a few possibilities:
1) Sheik is just Zelda in costume: The features of Sheik that we CAN see-- hair, eyes, nose, skin color, musculature-- do not match up with Zelda. To me, this seems to indicate that there is more at work than a simple costume. This is a possibility, however.
2) Sheik is a magical illusion: Is Zelda capable of magic? If she is, she might be casting some sort of illusion spell to change her appearance.
3) If Zelda is capable of magic, perhaps she ACTUALLY transforms into a man. Yes, penis and all: This is the most controversial of the options. :lol You can yammer about why you don't think this could be true, but in a world of magic, I don't see why it's not at least a possibility. From what I've heard (and don't quote me on this, I might be misinformed), the OoT manga that was released around the time of the game said that Zelda did ndeed transform herself into a man to disguise herself. Weird, I know. :lol
Bottom line? OoT, the game-- the ONLY source that really matters-- never says which of these is true. Therefore we can only speculate as to what the original character designer intended. Arguing about it is kind of pointless, I'm not sure there IS a real answer.