I'm not going to tell my dd to sit at the table or no food, She won't understand that. She likes to roam about and should be free to do so.
This says so, so much about your parenting style, much more than anything else you've written. Choose any style you like, and if it works, fantastic. If it doesn't work, you need to re-think.
The naughty step - works fantastically well, but you're doing it wrong - if he's complaining, the timer goes back to zero, don't leave him to do damage to walls etc, go back, tell him not to damage the wall, then reset to zero. It's not just a 4 minute sit down, it needs to be still and quiet, and keep at it until it is. Ditch the 'step' and make it anywhere you choose to seat him - that way it will work wherever you are.
Sit dd at the table, she's a person not a dog - or let her have the freedom to roam around and write another thread about her in a couple of years.
Stop locking your son out of the kitchen, it's a horrible and cruel thing to do, so upsetting to read.
No-one is blaming your DH for working, it just doesn't give you much 'time off' doing a bloody hard, repetitive, tiring job.
You need help to get basic parenting in place, or you just need to accept that the freedom to roam, eat on the floor etc etc will deliver a child that won't recognize the need to sit at the table and behave in Burger King. It really is your choice.