What does a sharp pain/ice cold sensation on a leg with chronic venous insufficiency mean, that also gets worse upon touching?

Depends: This could be any number of things. You should see a vascular specialist for further more detailed evaluation.

Depends: Venous disease causes many diffeent symptoms. If you have painful vv with palpation, this likely indicates ongoing inflammation related to too much pressure from valvular incompetence.

Swelling/ infection: There should not be any pain or discomfort unless you have a phlebitis or possibly an infection. If uour leg is swillen that can also be painful however. You should seek the advice a vascular specialist that has a special interest in venous insufficiency.