Boys are usually nicer at this age. Mine are very friendly. The girls are stand-off-ish.
Do you mean people-mean or aggressive towards other chickens?
Rhode Island Reds are generally like that to other chickens. My RIR is a sweet-heart to people though.
My goodness that first one has super long legs! :th
I'm not going to guess. The first one does not have enough of a comb/wattles for me to guess male, but the legs throw me off. I just don't know.