What kind of cat is this?

Red Tabby & white domestic longhair cat. No particular breed. Some long hairs get bigger then others.

He is a DLH, red boy with white. To translate: domestic long haired cat, red boy refers to how the orange coloration came about, so it becomes red with white. Some vets may simply put him as orange with white.

As far as weight, he is long haired, so a lot of it could be simply fur. Few have a scale accurate enough to get a decent weight of a cat. Unless they have a baby scale.

But the way to determine whether he is overweight is to look at his profile, and see the latter part of the link I am providing.

A domestic long hair, color is orange tabby

Edit

Some cats are just big. Mine (all fully grown) vary from 5 lbs to 12.5 lbs. Your vet will be able to tell you if he's normal (and just big) or actually over weight

It looks like a long hair tabby, but a vet could give you more info than anyone.