Re: feeling hopeless about my 4 year old
You need the book "Toilet Training in Less than One Day". It was written by psychologists in the 70s when developed a method for PT mentally handicapped adults. They trained people who had been in diapers for 40 years to use the toilet completely independently in ONE day.
They figured if they could do that, they could train kids who had been in diapers for "only" a few years. They were right. Children of ANY personality, ANY previous failed PT attempts, could be trained as long as they were at least 20 months, even mildly mentally handicapped kids.
It's complex. It's intense. It works--IF you follow it to the T. I have personally trained 3 of my own kids at ages 33 months (he was exactly like yours sounds, btw), 22 months, and 20 months, and helped my sister train her 28-month and 24-month kids.
I feel like it takes at least 3 days for most kids, although that might be because we did change a few things up (did practice runs in clean undies instead of soiled ones, because I didn't want that grossness drug all over my house). Maybe it would have been 1 day if we hadn't done that. One of them truly was totally trained in 4 hours, and we had tried everything you listed and more with that kid. Another child took almost a week, but she was too young I think at not quite 20 months.
Get the book. It works. I guarantee it.