I'm confused as to the range of brightness values associated with Landsat 8 Bands. I know that for Landsat 7 and below it has always been 0 - 255 but some of the literature indicates that Landsat 8 values range from 0 - 4096 since it's 12 - Bit. Is this a correct?
Landsat 8's OLI and TIRS sensors feature a 12-bit dynamic range which translates to 4096 potential grey levels. The products, however, are delivered as 16-bit images (scaled to 55,000 grey levels). See USGS' page on Landsat 8.