Fitbit Questions!

Hi everyone! I recently got the Fitbit Flex and love it! However I have a couple questions...
1. On the app, where does it say my TDEE? (The calories I maintain on)
2. What's the difference between the Alta, Charge, and Flex? Which one would you recommend?
3. When I do non-walking exercise such as the elliptical, how do I track that?

Thanks!

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