Problems with email notification to users and constant moderation of comments.

I’m very new to this so apologise if Qs seem trivial:

1) the email notification to each user when a new post or comment is made used doesn’t work..I really need this function. Help!

2) It seems as though each time a new post or comment is made, the administrator has to approve/moderate it.  This happens even if that user has had comments approved previously. How can I auto approve comments and posts made by users that have been previously approved?

Many thanks,

A