Thank you for your update in uc_event_3.zip. It took care of #23 (Non-Product Event becomes a Product Event). However issue #13, #15, #21 (Duplicate 'Add to cart') persists. The only way I could overcome this latter issue was to comment out lines 160-163 of uc_event.module. I don't like messin' with your code, so it would be great to have a more elegant fix.
// $node->content['add_to_cart_link'] = array(
// '#value' => theme('uc_product_add_to_cart', $node),
// '#weight' => 2,
Thanks again for your very useful module.