To your first question, you can change the meta tag like this inside template.php
function YOURTHEME_html_head_alter(&$head_elements) {
$head_elements['system_meta_generator']['#attributes']['content']= // whatever you want
}
To the second, you could create a form that changes the variable along these lines:
function YOURMODULE_admin_settings_form() {
$form=array();
$form['user_password_reset_timeout'] = array(
'#type' => 'textfield',
'#title' => t('User Password Reset Timeout'),
'#default_value' => variable_get('user_password_reset_timeout', 86400),
'#size' => 28,
'#maxlength' => 8,
'#description' => t('Enter the number of seconds for the user password reset timeout'),
);
return system_settings_form($form);
}
and then use that in a menu:
function YOURMODULE_menu() {
$items=array();
$items['admin/settings/YOURMODULE'] = array(
'title' => 'YOURMODULE Admininstration',
'page callback' => 'drupal_get_form',
'page arguments' => array('YOURMODULE_admin_settings_form'),
'access callback' => 'user_access',
'access arguments' => array('APPROPRIATE_PERMISSION_ON_YOUR_SYSTEM'),
);
// other menu items go here
return $items;
}