The units have a buff applied on creation that periodically use a create persistent at their current point with an offset behind the unit that tells the next unit in the chain to move to the point. Use a single period with no delay. You use a point and not a unit for the target of the issue order effect because you want the enxt segment to move to where the previous one was and not where it currently is.
A setup where the head unit is the only one creating the persistent would also be possible but the start/stop could be tricky.
Validator wise use a combination of Unit Compare Speed and Unit Order Queue validators (using Move but speed 0 = turning). You can look at my LEGZ demo map to see a similar setup.
0.962288686605982
Stuff like this is scary. Seems like this person had many dreams and passions that were shattered due to false promises and lack of simply basic real life resources. Although that being said. Working for Blizzard might not be as pleasant as it seems. They are likely to be very demanding of their workers. For me it would likely feel just like what it is: A job.