how do i enable phot stream
The page you came from, tells you how to enable Photo Stream in iPhoto.
You also have to enable it in the System Preferences > iCloud panel.
why is it taking so long to import photos
Hard to say, with no information on your setup. Are you on a fast Wi-Fi?
And is your device properly charged? If the battery on your phone is nearly empty, any upload to Photo stream will stop, until you have charged the batteries again. Or you may have exceeded your photo stream upload limits.
See these pages:
I'm going to piggyback this thread as I have a similar problem. Sometimes I disable my photostream and then turn it back on. But how long should it take to sync via wi-fi after I have enabled it again? Everything is charged, the camera app is off, my wi-fi is fast. I figured it would be instant but does it take a few hours to detect the photostream on my phone? Using a macbook btw.