I agree with almost everything you said, it is easy to see you have plenty of snow time experience. Just some words of caution:

Snow will always melt if you squeeze it hard enough (pressure melting). With cold, dry and fluffy snow that water re-freezes in the crystals without you seeing it. Over time, this process aids in turning fluffy snow into compact ice. If it's less cold that water may be visible or be able to soak into your clothes.

Fluffy snow is an excellent insulator. Solid ice is not. Even if you lie down in dry, powdery snow it is only a matter of time before your weight and body heat has turned that powder into icy, hard crunched snow - which (unlike powdery snow) will transfer heat away from your body. As you noted, that melted water will be freely available to speed up the cooling process in less cold conditions.

Bottom line: Always use a groundsheet or at least improvise something to that effect. Never lie directly on the ground or on snow.