A lot of people struggle to make enough money to support their household and provide food, shelter, and other things to themselves and possibly others.
1) It can be a huge emotional strain to work long hours of a job in order to make enough money, as well as physically exhausting because of the stress, perhaps lack of sleep, and even activities done in the work place.
2) As an insect, obviously he can't work a job. As a human he chose a travling job because it had a potential to make more money that he could use to pay off his family's debt.
3) His father had been providing money, but his business failed, and now the family has to rely mainly on Gregor to earn the income.
4) Yes, most people can, with hard work and some luck involved. If you get a job, and work enough hours, it will be easier. But if you can't find a job, for whatever reason, then money continues to be a big issue. You cant really survive in this world without money.
pg.1110 "Oh god, he thought, what an exhausting job I've picked on!"
