some maven basic problem

[maven apache]

I am new in using maven , so some basic problem confusing me:
1 When I create a new maven project how do I know which plugin to use?
2 the artifaceID and groupID respent what?
3 I have not use ant or other build tool before,so the pom.xml is stange to
me .
4 what is the difference between the maven dependency and the plugin in a
pom.xml,and what is the difference between the dependencies under the tag
"dependencyManagement" and the dependencies under the tag "project"?