Jim Cramer answers your Twitter questions from the NYSE floor and says UPS has lost its edge, and he likes FedEx. He says Facebook could go substantially higher and that if WhatsApp became public, it would be worth double what Facebook paid for it. Cramer feels good about selling American Express, which is not going to go anywhere. He was asked about Alcoa and says he likes the preferred stock over the common shares and isn't expecting a blow out quarter, but sees the stock substantially higher by year end. He's done with Isis Pharmaceutical, and in terms of Twitter, he thinks that's a buy to $60.