1: not all if the costs are energy related. In fact, the cost to build and maintain the transmission and distribution systems is quite substantial. But that cost is for an average amount of energy over a number of years so it’s hard to turn that into a floating market value
2: There are socioeconomic factors that need to be resolved. Someone who works nights can’t avoid using power during high price times as it may be the only time to do chores. Or someone who works two jobs who can’t afford any fancy equipment to time shift use.
I think this correlates with EV sales. In the places that have lots of EVs you will find employers that have chargers.
Elon Musk said it in one of his presentations, something like "we sell cars whereever we put in superchargers".
1) Unfortunately most workplaces don't have a place to charge your car. That should change
2) Laundry is problematic for households with 2 adults & a few kids. Multiple loads can't be automated that way, so not running laundry after 5:00 pm isn't an option many days.
3) You can can have a high-efficiency on-demand hot water heater with an external tank to hold X amount of hot water for use throughout the day. Heating your home is more problematic: the hot water loses about 5-10 degrees per cycle through the house & back to the boiler, so you'd still need to run the unit on cold nights.
4) Fridge/Freezer: I like the idea, but it could be a food safety risk... I'd rather see units designed with that particular use case & required insulation in mind to ensure food was always kept at safe temperatures, even if it meant paying the .30 for short spurts over night.
5) AC: I wish everyone would do this sort of thing already with thermostat timers. If you have a small apartment with window units, timers at outlets should automatically shutoff living/dining units. Bedroom should have a high temp (though comfortable enough to sleep through) set for the cutoff since you're sleeping anyway. If your home needs more than 3 window units, it's generally more energy efficient to get central air (though upfront costs are high) and you can get multi-zones to only cool the areas needed, further improving efficiency.
Basically, I think a lot of the things we'd do to deal with variable pricing could already be done to reduce usage.