As long as the landing gear is correctly serviced (lubricated), once it free-falls, either airflow pressure or application of a little 'g' should get the downlock latches to engage into 'Spring Lock'.
Spring lock is fine, except, it is not then firmly locked down.
only the mechanical lever lock will ensure that the landing gear will not collapse upon landing.
A primary design feature, at the time.
The aircraft could bite you and often fatally,
if you failed to get it right in all sorts of circumstances
Absolutely 100% correct.
The next in line, the DC-4, was a huge improvement, and not just because it has four engines.