Question

I have a question about cotton socks. Living in FL, wool socks can be somewhat warm (slight understatement, feet furnances is what they become). I have purchased some cotton sock yarn and was wondering how to approach the cast on, more or less sts? Fewer or more rows of ribbing, entire leg ribbed? Any suggestions welcome, any warnings even more welcome. Please help! They are for my loving mom for Christmas (so i can steal them back when she doesn't wear them ever).