Hi. We have also purchased Serangoon North Ave 1 resale flat, and your house floor plan is exactly the same as ours. We were very headache about how to renovate our house without using ID, but to only engage a contractor. We intend to renovate next year, after Chinese New Year. We have similiar ideas as yours, but was not sure if it is workable until we saw your house layout, we are sure the ideas will work out perfectly well for our house.