Yes, Japanese were imprisoned in camps.
Yes, I suppose some of them Self Deleted. (Self Delete is a big tradition in Japan)
But no, not all of them were detained and "never let out". Young men who were applicable for the U.S. military could be enlisted. However, these Japanese soldiers could only go to the war in Europe; not Asia.
Also, they weren't given $20; they were given $20,000 in the 80's as "reparations". These reparations were given to either the prisoners themselves or to their family.