Hi it will be CRF that was tested for at the vets- give them a phone if your unsure though.
I think i posted in the other thread about mixing what he likes with a renal diet.
Persist with it though, if he even eats some of the renal diet his protein intake will be less, making him feel less sick and more hungry.
It might be worth getting another appetite stimulant injection when you go back to the vets if you think it made any difference.

Also did they say what was wrong with his heart?

Stress to the vet that you want to do everything you can for him, and for more info on his conditions.
Its really sad they have just given up on him, but at least he has you to fight for him