This new feature was added recently which allowed you to search Friends faster as it would...

This is the one feature I love about MS is that you can kniw your entire library is your going forward. Another geat feature they recently added is network installs. Meaning if you have your old console and new console in the house but no external drive,
you can network all of your installed games from the old system to the new which might be faster than downloading on your internet connection.

Do you have any other friends on Xbox LIVE that play with the friend that you deleted? Also, I know some games allow you to search through players that you recently played with like Halo, for example. So, if you have any games with a similar feature you
might be able to find him that way. Otherwise, you would need to know his gamertag.

This is the one feature I love about MS is that you can kniw your entire library is your going forward. Another geat feature they recently added is network installs. Meaning if you have your old console and new console in the house but no external
drive, you can network all of your installed games from the old system to the new which might be faster than downloading on your internet connection.

Also helps if you have a data cap, as it is not downloading from Xbox but transferring via your router/gateway hub.

Because it's a brand new, recently added feature.

It may not allow you to delete the primary without adding a secondary; which would be his new email address.