this has nothing to do with PHP settings.
For 1, this is using the standard DW login / registration behaviors which we don't support. Support for the built in Server behaviors in DW should obtained from Adobe.
for 2, both the admin/index and account/manage/index.php pages are set to use user level authentication based on the MM_UserGroup session being set to 2 or 3
The login page however is not set to give any value to the MM_UserGroup session besides "":
$loginStrGroup = "";
//declare two session variables and assign them
$_SESSION['MM_Username'] = $loginUsername;
$_SESSION['MM_UserGroup'] = $loginStrGroup;
first:
$loginStrGroup = "";
then:
$_SESSION['MM_UserGroup'] = $loginStrGroup;
this code will mean that the usergroup session is always empty.