Please don't despair - it is the middle of the summer holiday, and most of the kids have their brains switched off! You may think I am joking, but it is proven that children genuinely do go backwards in their educational progress during the long summer break.
He's had a nice holiday, he's relaxed, the weather is hot and the 11+ is just not on his list at the moment!
I was in two minds about whether to move this post to the VR section, but I hope that Patricia will amble along shortly to give you specific advice on the question types that are causing problems. If it becomes mainly a discussion on VR technique one of us will move it over there.
There are some basic fixes for most of the problems you list, so just chill out and wait for Aunty Patricia.