Is a student owning a textbook that was given to his father for free from a school other than his own—for which he paid book fees—considered unlawful? And what should he do if his own school gives him the book later? And is it permissible for his friends to photocopy this book?

There is no objection to taking an extra textbook from another school if you have paid the book fees to your school, and both schools are affiliated with the same governmental body. If your school later gives you the book, do not take it. If you discover that it has separate fees, then pay them at that time. There is no objection to your classmates photocopying the book; it is their right until they receive their own copy.