Nice, I turned on the "force shipping regardless of weight" option and it worked like charm, thanks nicolas!
For the product quantity, I needed it after confirmation (along with the "Thanks for purchase" text).
It didn't echo anything with this code when put into 'checkout / end.php' nor into 'checkout / confirm.php',
so I wrote a javascript to take all values from the quantity fields at checkout,
it takes their sum, stores it as a cookie and shows it after confirmation (then deletes the cookie). Seems to work just fine.
Yet more questions :)
1)
in a new thread
2) [SOLVED] How can I request a client to accept conditions (with link to pdf) at checkout, before confirmation? (solved by adding it to workflow)