scratching

After my cat has pooped he always goes to the kitchen and scratches the plastic mat that his food bowl is on. He only scratches there and only after he poops, not after he pees. The litter box is in the bathroom nowhere near the kitchen where his food/the mat is, but without fail, after pooping...

Two of my cats have been scratching more than often, and I'm a bit worried. How often should a cat scratch themselves? They are scratching in the head/neck region, as well as in their ears, (can they scratch anywhere else?) Ear mites? They scratch about 2-3 times a day, that I see. They don't...