That is substantially correct. To help in the understanding, the pitch of turboprops is usually a balance of forces: Oil pressure driving the pitch to fine and further to reverse, and spring pressure driving the pitch in the reverse direction towards feather. Some turboprops have an additional isolated oil reservoir to quickly and positively feather the propeller in flight. A separate manifold in the prop dome channels this oil pressure to the feathering side of the pitch actuator, accelerating the feathering action of the spring. Otherwise the bleeding off of engine oil pressure may be so gradual the prop takes too much time to feather by itself.
If anyone has spent any amount of time around a BA341 operator's ramp (like ACA in Dulles) every now and then you will see a Jetstream with a propeller feathered. That's probably because the pilot either forgot or was late to engage the latches.
Some PT6 engines are equipped with blade latches - you will find these mostly on floatplanes like the DHC-6 and DHC-2T. Once started, the prop is in flat, i.e. zero thrust pitch. This enables starting the engine without going anywhere!
Sorry I can't remember the shutdown procedure on the HS748 - RR Dart engines. They too are a fixed shaft engine operating the prop through a RGB (reduction gear box). I believe they have automatic latches.
Good series of questions!