Looking through some of the sceneries available in the marketplace, it shows the inside of buildings. Is it possible to walk into the buildings or landmarks (Hana Airport and Space Needle are two examples) or is that the walk around that people are wishing for?

Yep, you can spend hours strolling around inside buildings - just use the Drone Camera - the details of which are dictated by the quality of the Developer - the people who made THAT airport, etc. We had a fun time a few months ago when Bristol Airport was released where there was everything inside …