Digital BW, The Print

Photoshop CS2 includes 8, 16 and 32 bit modes.  If you import a file at 8 
bit, can it be increased to 16 bit within Photoshop?  I noticed that when 
you do so the file size is doubled; but do you really have 16 bits/channel 
now? or was this controlled by the capture device, e.g. a digital camera?
Donald