Miles didn't hide in the room with Widmore and Zoe, he even had a cool line about not trusting the hiding spot unless there was a 'secreter' room. He said he would rather take his chances running through the jungle. So we'll definitely see Miles again.
They won't be answering all the questions that fans have because a lot aren't relevant to the story anymore and it would sound forced to just insert the answers into the narrative for the sake of it. Personally, I found the the explanation for the whispers to be weak when Hurley spelled it out for everyone. Sometimes things are more exciting when there is still a little bit of mystery.
The writers have also always said that LOST is ultimately about the characters and how they have gone through this journey over the past 6 years and changed as people. I've loved the mystery and sci-fi elements of the show also, but they weren't the main focus of the show as it was written. I also feel like a lot of answers were answered in some of the cool ARG things you could take part in online on all the fan blogs and message boards.
LOST became a full time hobby for me over the past few years, it wasn't just something I watched on Tuesday or Wednesday nights. It has become part of my daily life and I'm going to miss it terribly
I have faith in the writers ending it well but I'm going to be an absolute mess if the The Island is destroyed.
I'm Team Island all the way! I'll be live broadcasting watching some of the pre-show and finale before too many of my friends arrive for my LOST party. Check out my twitter if you want to come say hi to me and goodbye to LOST together.
