In LANDSAT 8 you can use 2,3,4,5,6,7, could attach the 1 and the 9. The following link is a diagram of equivalences between the wavelengths of LANDSAT 7 and 8.
You may detect land cover classes by using remotely sensed data, especially Landsat 8 (30 m spatial resolution). You should pay attention at the difference between "land use" and "land cover" definitions.
Because of you used to landsat7, you must use the 2,3,4,5,6, 7 band landsat8 (OLI Sensor) that corresponding 1,2,3,4,5,7 band in landsat7 (ETM+ Sensor).
Regarding to land cover and land use terms, when we do image interpretation into several classes, those classes are called land cover, not land use, right? From the image we can only detect land cover not land use. So, if we then talk about land use, what do we have to do to convert the land cover into land use types? Anybody has paper about translating land cover into land use?