Not sure about item 1 to 3 but about item 4; depending on the location, normally a single lot offered will be good to build a bungalow house (if it's located near main road or near any highway). If it is more than an acre I would strongly advise you to build terrace houses. from the total land area you probably need to surrendered 10% for open space (playground/greenery), 40% for carriageways, 6,000 sq. ft. for sewerage treatment plant which left the remaining you devide to 1,400 sq. ft. (if this is the areas you chose for each lot) and you'll get the number of terrace houses units.