check user status
is_user_logged_in() //if user is logged in
is_admin()// if user is admin
current_user_can('administrator') //user has certain role
get_user_meta( $user->ID, '_is_cool', true ) //check user meta customization
get url
get_option('siteurl') //index page
get_admin_url() //admin url
wp_redirect(home_url()) //redirect
wp_login_url(get_option('siteurl')) // login url with next path