How do you tell the difference between male and female 4-6 week old chicks?

[daisy06]

I've got two roosters that are my babies. I love them! Thing is they don't love me.

 

[Sweetlilbaby]

I've got two roosters that are my babies. I love them! Thing is they don't love me.

aren't you worried they'll fight? I plan in the future when we own a property (out of the city) to have two roosters but also to have it set up so if need be we could have two flocks of chickens if there ever were an issue. And in winter I wanna be able to free range the chickens in a huge garden (Just a dream).
Right now we rent a house in the city. Landlord doesn't care much about what I do here. But city laws No roosters, and only 6 hens. I'm thinking of keeping 8 anyway. I love chickens and I think the neighbors wont notice the difference in noise/smell between 6 and 8 chickens.

 

[daisy06]

I keep certain roosters apart by letting one free range and one kept in the pen. It has has worked out pretty well. The other roosters know not to pick fights with other roosters. I am planning though for multiple chicken pens so I can seperate roosters and hens to eliminate any possibility of rooster fights breaking out. I'd like to try to actually get something done before spring because I know roosters get rowdy in spring.