Preflowers show up as lil lumps where new branches come out of the main stalk (or thats generally the first place they show up). How long have your plants been in flowering? Unfortnately I cant see anything from the pics, the resolution is just not good enough.

Grow Marijuana FAQ, Cannabis cultivation - marijuana growing tips & photos This is a good resource to determine if yo have male or female plants. You should start seeing these about a week or so into 12/12, usually males first then females. The strains I grow it always seems that I see males about 4 weeks into veg, and females at 1 week into 12/12. which is kind of crazy.