Annual card fee is not applied to the first card. Not sure about other card types but on PC the first card is free. I have a USD and GBP Global card and was only charged the card fee on the second card I ordered.
Same here for the first card -- the fee was reversed a couple of days later.
You have to sign up for a Lounge Key account and link your cards. I think your entitlement is linked to your account and not how many cards you have, so you are still limited to 10 visits a year. Having both cards would help you prevent exchange fluctuations, but you will be charged the $20 annual fee on both of them.
I'm not sure you can link more than one card? On my LoungeKey account it very specifically refers to the "VISA Signaturecard ending with XXXX" next to my name, implying that it is linked to the card. And if I edit card I can only edit the existing one.
I cant figure out why it would decline?