I did the law clerk program at an Ontario public college a few years ago and will be starting law school in September. I think I can answer most of your questions.
The majority of my classmates were hired on after their field placement. I have classmates on Bay Street, in-house legal departments and small firms across the province. I know of starting salaries ranging from 35-45k, depending mostly on the size of the firm, but 60k+ is definitely possible after some years of experience.
As a law clerk, you will not have to worry about bringing in clients. Depending on the field, you may interact with clients a lot or not at all. I would aruge that the most valuable skill for a junior law clerk is attention to detail - no lawyer would want a clerk who constantly makes mistakes.
The work-life balance that you seek is very possible for a law clerk. In my experience, bigger firms are less busy and more flexible since they can afford to be over-staffed.
Feel free to PM me if you have any specific questions.