I have read that doing it freehand risks cuts in the paint. Should I be concerned about this when choosing an installer?
Regardless of who you choose, you should always find someone that you can trust working on your car. A skilled installer probably does free hand cuts on cars all of the time. The proper way of cutting a film on a car uses basically just the weight of the blade to make a etched line on the surface of the film.
Pre cut pieces can eliminate the need to make cuts on the car. Sometimes even with pre cut pieces, an installer may make minor cuts to do small adjustments. However, again, realistically speaking, if you are going to a skilled installer, you shouldn't worry too much about them cutting your paint.
The nice thing with PPF is because it is clear, you can see everything. Versus a color wrap, if they cut your paint, you won't see it until after the wrap has been removed. Additionally, most of the time, cuts are not made on the paint anyways. They are being trimmed in the body gaps of the car to get enough material to wrap around the edges.