They would have to be cut to length and then slid into the track. I am picturing a scenario where the slabs may be wavy or deflected and that each stud would potentially be a different length. Because in this case I want them to take axial load I want a tight condition that may not be practical to build.
Install the studs without a top track (maybe no bottom track either) and use clips instead to connect. Then you don't have to maneuver around the track legs or deal with the gaps at the ends of the studs because of the track corner curvature.
I'm inferring that you want the studs to bear against both slabs. Is this correct? If so, it is not necessary. As long as their connected to the track that should provide the continuous load path. I.e., from top track to screw to stud to bottom track. And there should be enough wiggle room that the studs could be positioned in place without too much effort.
Yes, you might have to measure each one and cut separately. Otherwise, you could install the track, allow for some slop, and the screws transfer the load. Contractor should be able to do this no problem if competent.
I just question bearing the slab on the studs. That makes no sense to me. It's like stepping on the top of a pop can and applying your weight till it crushes...
If you intend this to be load bearing. I would construction the wall on the ground, making sure each stud is fully embedded into the track. The wall will need to be constructed short a few inches (mm) in order to tilt it up into place without binding up. Then pre-load your supporting slab, insert steel shims over each stud location.
Add some fasteners to restrain it laterally.
If the wall induces negative moments by adding a support. Consider it pinned at this location and confirm it still works for positive bending. If the floor above will be exposed, expect a crack over the support. This could get around the negative bending check...
