Is it permissible for someone to perform Hajj if they borrowed money for it from their father, and they are able to repay it after completing the rituals? And is it a condition that the ihram garments be new and never worn by anyone before?

One is not obligated to borrow money for Hajj. However, if a borrower does so and performs Hajj with it, it is permissible, especially if he is capable of repaying the debt. As for the ihram (definition) garments, it is sunnah (definition) for the upper garment (rida’) and the lower garment (izar) to be white and new. If new ones are not available, it is recommended that they be clean. This is not a condition for the validity of ihram, but rather one of its sunnahs. A man must enter ihram in an izar and a rida’.