IOS – Can photos taken with the iPhone (and Apple ID) stream to the husband’s iPad (and Apple ID)

Photo Stream definitively only works for photos (or screenshots) taken after it was enabled.

As for your other problem: Yes, if you are logged into the same iCloud account on both devices and have Photo Stream enabled it should sync whenever you are logged in into a Wi-Fi environment (apparently Photo Stream doesn't sync over 3G).

What else can you try:

• Take a screenshot on the iPad, make sure you are in a Wi-Fi environment and see whether the screenshot appears on the iPhone
• Log in to iCloud from your computer (requires Lion or a recent Windows version of course) and see whether the photos get streamed there

You can use the same Apple ID on up to five devices.

I would reset the iPad and begin from scratch. I recently came across a similar problem with a new iPad and resetting it worked perfectly.