My dad got my mom their first Lhasa 30 years ago to replace me when I left home. She lived until she was 18 years old, and a year or so after she passed they got two more. Though I tease my parents, 1) for replacing me with a dog, and 2) for choosing a rag mop of a dog, they are fabulous dogs! They're smart and have great personalities. As to your dog's guarding you from the cat, I would talk to your vet about it. There are things you can do to convince the dog you don't necessarily need to be guarded.
Have fun with him - he's a cutie!