Minimum frame size



i was just playing around with wireshark a bit and saw that e.g. a arp request is only 42 bytes in length.

if i change the switching mode on my switch now from store-and-forward to fragment free, which should only switch frames with the minimum frame size for ethernet(64 bytes), would that mean that an arp request would be discarded?

how actually can it be that an arp request is only 42 bytes in length if the legal frame size for ethernet is 64 bytes?

thanks for any help,