I used to use Roto's light-gauge, but recently ordered Elixer's. I haven't put them on yet. As far as changing strings, it depends on how often you play and how much you sweat. I typically change out about every 3 months if I'm playing in churches or other "clean-air" places, but when I played smoky clubs and worked up a sweat, it was every 10 - 12 jobs between changes. I know most of you probably don't use finger-ease or anything, but down here in the deep south, it's hot and humid, especially in the 5-month summers we have.
I take WD-40 and spray a little in my palm and rub it on the back of the neck to keep the inside of my index knuckle and my thumb lubricated. Several players down here do that. I guess it's just the way my hands sweat. Does anyone else have this problem? I'm concerned that maybe I should use a guitar polish or something safer when I buy a Smith...