you can correct split to explode functions:
 
\user_address_select.php - 1
\user_files_select.php - 1
\user_product_select.php - 1
\admin\admin_payment_system.php - 2
\blocks\block_user_addresses.php - 1
\shipping\australia_post.php

You are right some of our files use old function 'split' which could cause errors in new
PHP versions. We have prepared a patch with updated files where we replaced 'split' function with a correct function 'explode':
http://www.viart.com/downloads/split_fix-4.zip
 
Regards,
ViArt Team

thank you!