Customizing the different sections?

Hello,

Let me first say that i’m a noob at web development and especially wordpress.

I managed to get a decently working site with the available features, but i’d like to know hot to remove/hide certain parts in a page.

For instance:

-How do i hide/remove the excerp, author, comments, tag… part in a certain section (for instance Add Page, Post…)

I’m making a user generated page and i as an admin only want the users to have the bare minimum of what they can tweak.

For “Posts” i just want them to see “title/text” portion and the “publish” portion.

Is there a simple way of customizing the back-end pages?

Is there a plugin that let’s me choose what is available?

tnx