Sexing chicks

I got some eggs from my brother who has mostly bantams and a few hens and now have I have 2 chicks that are 7 weeks old. The one we think is male (black) has a comb & wattles growing but he is smaller than the other (white) which doesn't. Is it true that females tails pop out earlier and that cockerels should be starting to grow spurs by now?  Seems like lots of random questions but I don't want to wake up one morning to hear crowing which the neighbours won't like. 

what breed are they? Some chickens cannot be sexed until they crow or hatch. Oh and hens can also grow spurs