I strongly recommend you NOT buy Cremona M Speakers used from a private party in Poland. All of your above questions raise too many red flags regarding this purchase. It is not worth the grief and aggravation you are going to have if anything goes wrong. You will be much better off purchasing them used from a local retailer.
Buying these speakers from someone in Poland is not worth the risk regardless of the selling price or other claims regarding this transaction.
Buying these speakers from someone in Poland is not worth the risk regardless of the selling price or other claims regarding this transaction.