The original article stated that a train wasn't able to start because the caboose's brake was on, so presumably the answer to the second question is yes, at lea

The original article stated that a train wasn't able to start because the caboose's brake was on, so presumably the answer to the second question is yes, at least for that car. Presumably the first question would depend on the slope of the incline (although if necessary other brakes could be engaged after their cars' couplings were compressed). Anyway, all just conjecture on my part!