What is the ruling on wearing the ihram with pins or clips, and does this act make the ihram like regular clothing?

The basic rule is not to fasten the ihram, but rather to place it over the shoulders. However, it is permissible to fasten it out of necessity, such as for a cook. As for fastening it from the neck down to the navel, making it resemble a shirt, this is questionable in terms of its permissibility, because then it resembles a shirt, and the Prophet, may Allah bless him and grant him peace, forbade the muhrim from wearing a shirt.