I can help you with part 1
Methane, CH4, would have the lowest boiling point among the three since it has the lowest number of carbon and has no functional groups. Methanol would have the highest boiling point since it has a functional group which contains hydrogen bonding which much stronger than the one in CH3Cl. Hope this helps.<span />
The opportunity costs of working part-time while attending high school could be studying time, grades, and your own free time. It depends on the person, how they do in school, but if it were for me, I would say the benefits outweigh the costs. I have enough time to study and still get good grades in school.