Downtown Portland the Pearl district are quite walking and biking friendly if you want to live in a more urban environment with the housing options mostly limited to condos and some townhomes. Outside of downtown, the most popular neighborhoods for being walking and biking friendly are probably Hawthorne, Alberta, Sellwood, and Multnomah Village. However, these are all fairly well established and are not the most affordable neighborhoods. The up and coming neighborhoods with similar amenities might be St. Johns and the Mississippi areas in North Portland. All of these neighborhoods have cafes, coffee ships, and restaurants to enjoy. You can read more about many of them on my website and see properties available in the the neighborhoods.
Hope this helps.