We love our CNAs in surgery/trauma ICU. The techs here are crosstrained to cover unit secretary tasks, so when you are not helping the nurses, you are answering the phones, printing forms and ordering supplies.
In my ICU, CNAs do not do vital signs, empty foley bags or many of the things you mentioned; the nurses do those.
What keeps you busy is assisting the nurses with turning the patients every 2 hours, helping the nurses boost patients up in bed, helping with log-rolling patients on full-spine precautions, helping get people out of bed to the chair, helping turn and clean poop, helping slide patients on to the stretcher and pushing the stretcher to CT scan, MRI or wherever the test is.
The work is still pretty physical since almost all of our patients here are total care. The nurse is almost always assisting you.
Between the secretarial chores, and patient turning, our techs are also our equipment wranglers. If we need a rapid infuser or something like that, CNA knows were to find it. They keep our bedside supply carts stocked too.