I'm a few years into my job at a SLAC (still assist prof, but tenure track):
1) First year on the job was 50-60 hrs/week. Largely consisted of class prep, grading, recruiting students to work in the lab, getting research off the ground, etc. (by the way, class prep is a time killer, especially if you're relatively new to teaching.) Now that I'm a few years in, I'm working about 40-45 hrs/week. Although class prep is considerably shorter, service/committees are the huge time suck now.
3) I'm generally happy with the balance, but like other new profs, I don't have parenting responsibilities yet. Newfacultymember2011 is correct in that there is more flexibility/freedom than in other positions, but you should try to avoid making a habit of taking off early. It may be more of an issue at a SLAC, but other faculty seem to notice if you're not around as much as them and/or leave in the middle of the day. SLACs are like small towns — everyone knows everyone, and news/rumors can spread quickly. You don't want to come across as taking advantage of the freedoms associated with your position — at least not until tenured!