I've never flown AA from BCN, but have flown them many times from Latin America and once from LHR. At those stations they have provided the US entry documents at check in--usually in a ticket jacket IIRC. Are you sure you weren't given one at BCN before you boarded?
I am 100% sure I was not given a US customs declaration form at check in. As a matter of fact, when I fly AA out of LHR, I'm not given a US Customs Declaration. But I suppose it's the same thing namely when I get one on the plane flying out of Heathrow, it's also in the local language. At least I can read those 
No, AA's IFE isn't great, but I find that the time passes nicely if I bring a book and/or an iPad along. It's not a bad idea to pack them even when flying airlines with superdooper IFE, since failures aren't all that uncommon.
Actually, you're right. AA is at least 15 years behind say Virgin Atlantic in their onboard entertainment. But my FF is with American!
As for the diet coke/coke zero/coke light, isn't it all basically the same garbage? Several shovels of aspartame mixed with various other chemicals? Ugh. I recommend good old water, or springing for a nice nutrient-rich beer or a heart-healthy vino tinto. AA usually carries a decent selection of that stuff.
Of course none of that stuff is good for me. But I have a caffeine addiction that isn't cured by doffee. At least it's opened up a nice discussion without too much name calling.
