Question
How Far should this tree be planted from my house, so that i wont experience root problems with the cement foundation and the slab flooring

Answer
willow roots do not generally cause problems with the foundation since the roots a generally small a fibrous. BUT the roots can cause problems with sewer pipes. Willows grow naturally near water and hence they seek water and if a sewer line is damp or leaking they will invade the pipe and clog it up. the roots will also take over a garden so I would plant the willow away from the house  and not over or near a sewer line or septic lines. keep at least 20 feet from these lines.