With this insanity going on, I'd get a water timer as already suggested. I have hair that I can sit on dry and it's hyper curly, so it's knee length or so straight I'd guess. I can't do a full wash of my hair in under 15 minutes, but I can do the quick version in the shower in under 10.
Also, if he's going to behave like a 2 year old, he gets the rules of a 2 year old. No door shut, at least until he is going to get directly in the shower. Dad has to sit in the bathroom with him for the shower. Which may mean night showers would fit the schedule better, plus with direct supervision until the bad habits are broken and having to take the time at night cutting into play time, so there is a secondary reinforcement.
As for the stove issue - no, you can't deprive them of food, but it doesn't have to be a nice, home cooked meal. He can get a cold sandwich and some raw carrots for dinner, sit at the table where you can watch him, then go directly to bed. Nice meals that are hot and require silverware are a reward, plenty of people do fine with less. DH and I did fine with less for many years.