i would recommend you find a copy of the book: Julius Shulman: Architecture and its Photography
Julius Shulman Book Review
looks like its out of print now but the library may have it. you wont learn anything about using a camera to get marketing photos but youll get alot of ideas about composition
without a large format camera it can be tough to get pro looking shots. i wouldnt worry too much about it. your photos look fine. the kitchen shot looks very good. with a tripod and proper metering, you should be able to get nice shots and ultimately the home should sell itself if you have presented it's features clearly