Admin user roles/permissions

The “Contributor” role has very little access to anything on the back end but can created posts.

  • delete_posts
  • edit_posts
  • read

http://codex.wordpress.org/Roles_and_Capabilities#Contributor

For comparison, an ordinary “Subscriber” has the last of the three, so “Contributor” has only two extra capabilities.

I am not quite sure what “access to specific plugins” means exactly but I am nearly certain that you can’t do that with Core WordPress. If you were more specific about what you want I might be able to do better.