There are two distinct "distances" that this question may refer to, and you are probably interested in both:
1. Shooter to Target
Keep in mind that the shooter does not have to be close the camera at all. We have actually had the shooter a few hundred feet from the targets before, and just left the webcam up closer. As long as the laser is bright enough to be detected by the time it reaches the target, LASR will work just fine.
Yes, you can have targets at different distances and different angles as long as the webcam can see them. This can be accomplished by leaving the whole computer/webcam setup closer, or utilizing USB extensions. If you are utilizing extensions, make sure that they are rated for use with webcams. Longer extensions will usually require repeaters.
2. Webcam to Target
The farther you get the webcam from the targets, the more targets you can fit into view, and "wider" shooting area you can have, but if you don't have the space or the need, feel free to put the webcam as close as you like. We generally recommend anything from 5 to 30 feet for most folks, target to webcam distance, but we have even gone beyond that on several occasions with no issues:
Your maximum distance for webcam to target is going to depend on different factors, including target and lighting, but mostly on what resolution your computer is capable of handling with the LASR software. As long as the laser impact is bright enough to be detected, you can place the camera back as far as you like, however, at a certain point, you may find that the fine details of the target are too degraded, or that the fine details of the laser impact (including brightness) are lost to the point of not being detectable anymore. Obviously, the higher resolution your computer is capable of handling with LASR, the farther back you can put the camera without image degradation. You can read more on that at this link.