Gratuitous ARP&Regular ARP Questions :)

1. Does a gratuitous arp also checks and informs a redundant MAC-Address within the same broadcast domain? Simply does a gratuitous arp also check and compare sender's and receiver's MAC Address? I am guessing it does because when I change the MAC Address, it sends the gratuitous arp.

2. Let's say 10PCs (A to A to J) are connected to SW1. Right after I give a static ip to PC A, PC A will broadcast a gratuitous arp packet. My friend told me that there are two types of gratuitous arp: first one is request and second one is reply. He also said that when PC A broadcasts a gratuitous arp (Could be a request or reply depending on OS), if it is a request gratuitous arp, other 9 PCs would add PC A's MAC and IP on the ARP Table. However, if it is a reply gratuitous arp, other 9 PCs won't add PC A's info on the ARP Table. Can anyone tell me whether it is correct info or not?

3. Let's say 10PCs (A to A to J) are connected to SW1. When PC A pings PC B, PC A will broadcast the ARP packet first to figure out the PC B's MAC address. Again, my friend said that when 9 PCs including PC B receives PC A's ARP request packet, they all add PC A's info on the ARP Table even though only PC B will reply. Please let me know whether he is right or not.