You don't want to know

They take the money back out of your account. Send you a letter explaining why the chargeback happened, you can then respond and try to fight it. They have a 1000 ways to get out of it. They almost always side with the credit card holder and you are out of money and the part.
We just got dinged with a Amazon scam / chargeback. We got an order on our site, CCV matched, Address verified on the AVS system, billing and shipping address matched, so we processed. 2 weeks later we got a charge back. Started looking in to it. By chance this was an existing customer. He said he ordered the wheel spacers off Amazon and was a little surprised that it showed up in our box (however did not really think antything of our invoice in the box with a higher price than his Amazon order).
So he ordered parts, got parts, paid for parts, all is good on his end. Scammer has his money.
Scammer bought from us with a stolen card, but since they had all the customers info from the order they received on Amazon, they must have set his address to the billing address of the card. So when we ran the card the scammer used to place the order, it verified fine.
The issue is really how the credit card merchant processing authorized this transaction or how the bank changed address on the stolen card. We can't figure that one out.
The only tell tale sign of these orders are typically some weird email address. Just some FYI,
As for lost packages. There is no right or wrong way. We state on our site that we ship "signature not required" unless requested. If the package shows delivered and client never got it, they are pretty much on their own, but we will assist where we can.
When lost in transit, we file the claim and resolve with the carrier / reship the parts to the customers. However we do not use the USPS expect for some small items. Also we go to great lenghts to use correct boxes, pay attention to the weight rating of said boxes and do not exceed it. Otherwise with damaged packages you just get the "insuficient packaging" excuse. With the carriers we use, we have to initiate the claim.
Not sure on value of shipment, but mostly the carrier asks you what is your replacement cost to ship the item again. So that is a little gray area on small packages. Freight is a whole other ball of wax.