Your questions are answered on the following two privileges sub-sections:
- Flag Posts
What happens when I flag something Offensive or Spam?
The offensive and spam flags are designed to automatically eliminate
truly offensive posts through the collaboration of the community.
3 flags -- post is banished from the front page. 6 flags -- post is
locked, deleted, and the owner loses 100 reputation. Users with the
Moderator Tools privilege can see how many offensive flags a post has
accrued, and may opt to flag it themselves.
What happens when I flag something Requires Moderator Attention?
You'll be required to enter a comment briefly explaining what the
problem is. After that, these moderator flags go in a special high
priority queue visible to all moderators. We take moderator flags
quite seriously; rest assured that they are all followed up on!
- Moderator Tools
When should I act on vote-to-close and vote-to-delete flags?
These flags will appear on the list of flagged posts in your moderator
tools. You will not be able to see who cast each flag, however.