I'm running Grey Wolves and I am able to go from the surface to
periscope depth while doing "0" knots. Then I went from periscope depth back to the surface. Kinda neat to watch the Sub just rise out of the water.

I Haven't tried to go deeper while stationary from
periscope depth so don't know.... I did lay on the bottom one time in the vanilla game but haven't tried it with Grey Wolves. I did not time compress while there tho....