I'm a medical physics resident.
To get into medical physics requires at least a master's degree. 1.5 years is very optimistic in my opinion. Realistically you're looking at 2-3 years for that. (There's a lot of course-work in medical physics). It's prefereable in my opinion to do a Ph.D., since it makes you more marketable when it comes time to look for a job and puts you in a better position to do research.
Residencies aren't absolutely necessary to get work, but the clinical aspects of medical physics are tough to just "pick up" and so a formal set of rotations is very helpful in establishing your clinical skills for the rest of your career. Further, a residency makes you more competative for the better jobs and gives you a good foundation for writing your board exams.
The pay for residents, from what I remember from recent salary surveys is ~ $40-50k (USD) ballpark, but it varies from place to place and juniour physicists (those with less than 2 years experience) can make substantially more.