why are some of my users awaiting activation when I have email registration? Is that b'cause they did not complete registration by clicking the url in the welcome email?
Yes, users are placed in the Awaiting Activation when they register until they click the link in the registration email. This is to ensure that a valid email address is used. You can disable this, or select a different registration type in the User Registration and Profile Options setting group in the admin cp.
You probably don't want that; you'll get spammers...