Is it permissible to frequently curse Iblis and to say, "May Allah forgive you, Adam, for what you did"?

It is permissible to curse Satan. As for saying, "May Allah forgive you, O Adam," there is no objection to it, because Allah accepted his repentance, and one who repents from sin is like one who has no sin. It is permissible to supplicate for the prophets with mercy and forgiveness, but one must be careful that the intent or context of the phrase does not allude to Adam's shortcomings, as it is not permissible to utter such a thing. This does not prevent expressing words in the form of supplication, as it may be intended as belittlement and backbiting.