Allowing user to edit only the page content and some custom fields in wordpress

This is the site:

http://www.backpackers.rs

Using “User Role Editor” i have user group that can only read and edit published pages so i can have as many users as i want in that user group and they all will have only one published page on their own so they can edit only that page.

Now, this is how a user in that user group currently is seeing “edit page” page:

http://i39.tinypic.com/rwuesh.png

What i need is to disable all those things that have a red border around it + something with custom fields. So i need to disable these things for user in that user group:

1. ability to change status of the page
2. entire “Attributes” block is something that he/she must not see or be able to change
3. ability to change something in “Discussion” block
4. he/she shouldnt see “Page revisions” block
5. i need a way to give those users ability to use only some custom fields. Currently we have 6 custom fields, and i want to give these users ability to only use 4 of those custom fields.
6. i need to disable these users from creating new custom fields.

I dont need complete answers for these things, something to get me started is really what i need. I have been reading codex a lot, but still didnt find something to help me with this, so basically any answer is more then appreciated!