Got a PL154 and PL310 here.
1. Doesn't take long. Process is: (a) set the right knob to middle, (b) set the left one to near where you want, (c) trim with the right knob. Takes no effort at all.
2. No. It's easy enough to set precise voltages.
3. Yes but only if the output capacitor is discharged. The instantaneous current can be quite large otherwise. If you're going to do that, set the current limit, short the terminals, connect the circuit, power it up, then remove the short. There is no overshoot that I could measure. I regularly use them to drive LEDs.
Best bit with these is the output switch also sets the mode. So if you set up the voltage/current while the supply is off and the display shows the set point. When on, it shows the actual output.
Really though, I require a precise voltage perhaps once a month or two for what I do so I tend to just use the coarse control.
Supplies are completely 100% quiet. Not even any transformer hum.