How much you can fit in to the iPad will depend on what you put in it. I have a 32GB ipad and I have 1500 songs, four 2 1/2 hour movies, over 90 apps, 25 pod casts, and still have I have 9GB of space left over.
The 16GB iPad can hold up to 4000 song , depending on the size of the song. For video it will depend on the quality of the video but in can hold up to 20 Hours.