1. Will mowing the grass blades shorter converse water ?
No, shorter = will burn faster in the Cali heat
2. Are there effective "wetting agents" which are proven to converse water ?
Sorry, I don't know
3. Is applying fertilizer unwise because it promotes growth ?
Just don't do it. It will burn
4. How about turning off irrigation until the grass shows a lack of water, such as the failure for the blades to erect after stepping on the blades ?
Grass will fall in dormancy and turn yellow. It will NOT die.
5. Bluegrass is said to have shallow roots, so what about watering shorter and more often ?
Mow less and keep it tall so that it can have it's own shade and stay humid longer. Also, mulch!