That's weird because 'jpg' is listed in the supported file types:
	
	
	
		PHP:
	
	
		$attachmentConstraints['extensions'] = array('jpg', 'jpeg', 'jpe', 'png', 'gif');
	 
 
You don't need [bd] Paygates to add support for custom currencies. 
You'll have to edit the template 
thread_list_item, search for:
	
	
	
		Code:
	
	
		{xen:link "threads{xen:if '{$thread.isNew} AND {$thread.haveReadData}', '/unread'}", $thread}
	 
 and change that to:
	
	
	
		Code:
	
	
		{xen:if $thread.classified_id, '{xen:link classifieds, $thread}', '{xen:link "threads{xen:if '{$thread.isNew} AND {$thread.haveReadData}', '/unread'}", $thread}'}
	 
 
I'll have to check that out.
That is as expected: giving the user the freedom to have a classified icon or not.
There's nothing to fix because isn't a bug. I might not be able to express it properly so if someone can give me a helping hand that would be awesome.
Like I said before, what you are thinking of is only a single use case: force a user of a certain user group to use a certain package only.
But what the system does is, for example:
There are three users: 
John, 
Jane and 
Dave.
All of them are, by default, members of the 
Registered user group.
John is also a member of the 
Staff, 
Donors, 
Active user groups.
Jane is a member of 
Donors user group.
And 
Dave is in no other user group.
Now, you have four packages:
Basic: available to all user groups, including 
Registered.
Donors: available for those who belong to the 
Donors user group.
Active: available for those who belong to the 
Active user group.
Staff: available for the staff members.
So:
John will be able to choose between: 
Basic, 
Donors, 
Active and 
Staff (so all four).
Jane will be able to choose from: 
Basic and 
Donors.
and 
Dave will have only one selectable package: 
Basic.
This IS how I envisioned the package module to work and it works just like that. I am not entirely sure why you want to restrict your users to a single package only, why wont you give them the freedom if they want to pay more or less, depending packages they are allowed to select.