Real Estate / Down-payment; are many contracts made without any down-payments in Poland? [6]

I had a discussion with a real-estate agent who declared that many contracts are made without any down-payments in Poland and he also had the opinion that a buyer can change his mind and claim money back for almost any reason. In my opinion he should only be able to get his money back for reasons that are mentioned in the contract. Could someone please tell how is the common procedure? This refers to "second hand" sales of apartments.

Real Estate / Contractual issue, a notary agreement to sell an apartment in Poland [2]

Could anyone please comment on this issue:

I had made an agreement to sell an apartment and was at the notary office together with the buyer to finalize the deal.
Following clause was included in the document: "The parties are informed about the Polish civil law no 359 (?) which makes the parties tied to this contract for a period of twelve months."

I tried to convince the notary that this was unreasonable in case the buyer should fail to come forward with the payment as agreed. I mean, if he should not obtain the credit from his bank how could I be staying with the contract for twelve months not beeing able to close a deal with an other client?

I was told that this is the law, my question is of course if it's correct?