A restaurant, coffee shop, bar or similar drinking/dining establishment is classified as a "retail sales and service". Industrial zones (lots of locations in the central east side) will have limitations on non-industrial uses, so you may or may not be able to fit into any particular industrial location. Call one of the planners at (503) 823-7526 to make sure that there are no zoning issues with a location.
A change of use, for purposes of the zoning code, may require bike parking, additional vehicle parking and/or changes to the parking, or paving and landscaping on the site. Exterior changes to a building, in many areas of the city, must go through a design review process to make sure that the proposed changes meet any special design guidelines for the area in which the project is located. The requirement for design review can be triggered by a very minor change, such as installing a replacement window that is not identical to the original.