1. You need to consider the building owner as the landlord. Being a shareholder-employee has nothing to do with whether or not the person owns any property or that this specific property is what they own. But, since your person is party to both entities (ownership and also his own corporation) you need to read the self-rental considerations; these matter to the tax preparation.

2. Is this even the same person? Because your shareholder-employee doesn't have a home office. His employer has rented office space.