Is money obtained from a lottery prize from a publishing house lawful (halal)? And is it permissible to use part of it to pay off usurious debts owed to a bank in France?

If the monetary prize is not linked to paying an amount other than the price of the newspaper, and the purpose of buying the newspaper is to read it, benefit from it, and then participate in the competition, then it is a permissible prize. It is permissible to use it to pay off debts, with the caveat that it is not permissible to pay usurious interest if it is possible to refrain from paying it without a significant legitimate harm.

However, if the prize is impermissible, it is not permissible to take anything from it, and it must be spent on the welfare of Muslims (such as aiding the poor and establishing schools), unless one is compelled by a legitimate necessity (such as ruin or long imprisonment), in which case it is permissible to take only what alleviates the necessity, and the remainder should be spent on the welfare of Muslims.