In order to upgrade the Magic's horn, they'd have to rip out the current horns. I'm not sure if the Dream horns are digital, but the Magic actually have the different horns that make up the notes to When You Wish Upon A Star. I do think that the Dream horn has a different "timber", so it just doesn't sound the same to me
Tea with Wendy is an event that you can sign up for with your kiddos to go learn how to take a "proper tea" with Wendy and the Mad Hatter in Studio Sea. It's not really tea, it's apple juice, but it's cute for the kids. You do go to Guest Services to sign up as it's space limited. We've done it once, probably don't need to do it again.
And yes, Okim and Mikey were our server and assistant server on our Med cruise, we loved them! We actually got a picture of our family with Okim and Mikey, plus Raphael who was our Server on our Halloween cruise in 2008 (our assistant server Daniel went to the Dream), plus Brendan who was our server on our very first Magic cruise back in 2006! We saw Brendan coming into our first dinner, and he remembered us which just floored me! Either they have fantastic memories, or Disney does really good intelligence for those servers who've been with the company a long time to remind them of past cruisers

, either way, it's really nice.