Probably some clarification is needed here. First, will not address the contact-less use that seems to be answered.
Regarding the PIN on the Costco card...They are saying that their card is a Chip and Signature with a PIN for Cash Advance, that is accurate. In Europe however, if you use the card for purchases at a manned sale, a slip will be printed out for you to sign. For small sales at unmanned kiosks or ticket machines, you may be prompted for a PIN, since systems expect a PIN for use. People have reported that entering your PIN for Cash Advance will work in these cases, sometimes any combination of numbers, sometimes nothing. I would not assume that your assigned PIN is acting like a Chip and PIN card, it is more likely that your card has a Cardholder Verification Method (CVM) for low dollar transactions (under $50 or $100) so if the European System gets a PIN, it passes the transaction onto your Cardholder, who ignores the PIN and just authorizes the transaction based on Dollar amount. If you tried to use the PIN for a $200 hotel bill, it would likely bounce. Bottom line: While a Credit Card Cash Advance PIN may be useful for some low dollar transactions, it is not a Chip and PIN.
Regarding if you do have an American Chip and PIN Credit Card, due to ranking of your cards CVM's; signature is still likely first in order, so many places in Europe you sign a slip. If that is not an option where you are making the transaction, then it will prompt you for a PIN. There are maybe only a half dozen cards issued in the US that are PIN priority that will always prompt for a PIN if available,
Regarding using your Cash Advance PIN for a sale and being concerned about being charged for a cash advance, I agree, this is not an issue. You should however read the fine print of your agreement, some transactions will be charged as a Cash Advance, regardless of whether a PIN was used or not...for example, buying Chips at a Casino...it can be an odd list of items, but worth being aware of.