Yes, there are some keystoning effects, but they'll look different than on a regular projector. Keystoning is most visible on regular projectors because the image is projected as a plane through a lens, and that entire plane may not have the same distance from the projector lens; this can cause blurring, etc. On laser projectors, the laser beam is deflected by a pair of mirrors, so while there can be vector distortion keystoning effect due to distance, the laser dot itself rarely looks out of focus. In other words, if you're projecting a ruler on the wall, the ruler may not have consistent unit distances, but at least it'll look sharp.
In any point-source projecting system you can only avoid keystoning if you compensate for it by scaling the graphics. Even rendered 3D graphics suffer from the effect (or rather its inverse).
As for accuracy... that'll depend on your hardware. Even if your signal has a high resolution, the mechanical aspects of the galvos used for beam deflection may prevent accurate reproduction of graphics. If you really want accurate measurements you'll probably need something like a spinning mirror that is timing-accurate and then something that projects a beam at specific intervals that represent distance units. Such laser measuring tools are in a different ballpark compared to most laser projectors.
