How can i change BitField Values

[dn lodge]

I am creating a Custom Product for vBulletin (my first time) and i am picking up the format etc. from this site slowly.
Now, i am stuck on Bitfield xml file.

i have created a bitfield_product.xml file. vBulletin is picking up this file and showing the options, and its working nicely. Following is my BitField file
<?xml version="1.0" encoding="ISO-8859-1"?>

<bitfields product="_vbhostreview">
<bitfielddefs>
<group name="ugp">
<group name="vbhr_permission">
<bitfield name="vbhr_canapprovehost" group="vbhr_permission" phrase="vbhr_canapprovehost" install="5,6">1</bitfield>
<bitfield name="vbhr_candeletehost" group="vbhr_permission" phrase="vbhr_candeletehost" install="5,6">1</bitfield>
</group>
</group>
</bitfielddefs>
</bitfields>


Install/Uninstall Code in product file

<installcode>
$db->query("
ALTER TABLE " . TABLE_PREFIX ."usergroup ADD vbhr_permission INT( 10 ) UNSIGNED DEFAULT '0' NOT NULL "
);
if (is_newer_version('3.5.1', $vbulletin->options['templateversion']))
{
// Rebuild Bitfields
// Do this for vBulletin < 3.5.1 *ONLY*; later versions rebuild
// automatically and calling the builder in install code causes
// the bitfields NOT to be rebuild correctly
require_once(DIR . '/includes/class_bitfield_builder.php');
vB_Bitfield_Builder::save($db);
build_forum_permissions();
}
]]></installcode>
<uninstallcode><![CDATA[
$db->query("
ALTER TABLE " . TABLE_PREFIX ."usergroup drop column vbhr_permission"
);

if (is_newer_version('3.5.1', $vbulletin->options['templateversion']))
{
// Rebuild Bitfields
// Do this for vBulletin < 3.5.1 *ONLY*; later versions rebuild
// automatically and calling the builder in install code causes
// the bitfields NOT to be rebuild correctly
require_once(DIR . '/includes/class_bitfield_builder.php');
vB_Bitfield_Builder::save($db);
build_forum_permissions();
}
]]></uninstallcode>

I have 2 questions:
1) How do i make the default value to Yes (right now its making it No)
2) I see there are some HELP files with other settings (? beside each setting). How can i provide help for my custom permissions??

Thanks in advance.

I changed one line, not sure if its correct way to do it, buts it seems to be working

i changed
$db->query("ALTER TABLE " . TABLE_PREFIX ."usergroup ADD vbhr_permission INT( 10 ) UNSIGNED DEFAULT '0' NOT NULL ");

TO
$db->query("ALTER TABLE " . TABLE_PREFIX ."usergroup ADD vbhr_permission INT( 10 ) UNSIGNED DEFAULT '3' NOT NULL ");

Having default value of 3, it turns Both options on.

But, then if i change some options later on, it doesn't seem to work?

ANyone Please??
or give me a link to some tutorial