Thank you very very much, Nicolas! This is what I need. There is just one small step to perfection missing.
I have customised export.php (attached) to view only selected columns in desired array and when I apply this plugin, some columns are empty (order_created, order_product_code, order_product_quantity, order_product_name, order_product_price, order_payment_price, order_shipping_id, custom filed fa with custom invoice number, comment).
I have tried to use original export.php, but it didin´t work at all - I get syntax error, unexpected ',' when I try to export orders.
Could you, please, give me a hint what and where do I need to correct? Is there some conflict between this plugin and customised export.php or there is something missing in the code?