You see buildings similar to this all over the older sections of Memphis - Midtown, South Memphis, North Memphis. I can think of at least 2 more nearby this one that have been converted to single family or other use. This was most probably a neighborhood grocery - store below, family lived above. Here's an interesting article that explains the concept: http://www.memphismagazine.com/Memphis-Magazine/November-201
As to the architect, who knows? These buildings were probably standard for the day with many being built from similar plans. Style- Early 20th Century Commercial?