Editing access to site-admin features for user levels

edit: I found the answer to part of my question in wp-admin/menu.php, edited the levels there;

How can I change the default page that is loaded after a user clicks on ‘site admin’, after logging in, or after logging out?

I’d like ‘site admin’ to direct users to their profile, and after logging in or out, I want them to be redirected to the main site homepage…