1) What is your favourite smell/scent and why

Probably the smell of fresh air when you have been stuck in a room for too long. Or the smell of natural landscape (like when you step under the trees to enter a forest and your senses are assaulted all at once by the smell of trees, leaves and vegetation and the sound of modern life being replaced by the primeaval pseudo-silence. (à la R.E. Howard). Or the seaside on an island. And certain perfumes.

2) If you could be really good at only one thing, what would it be and why?

Stay healthy because poor health restricts the scope of what we can do (though everything you do feels like an achievement, like Kev wisely explained in another post).
Or learn to be more detached from things, not get irrated by people’s annoying habits or modes of behaviour; be able to let petty things pass without feeling really angry about them. Save the anger for important things. (and hopefully avoid an ulcer).

3) Would you cheat if you knew you wouldn’t get caught?
As some posters have said, depends on what you are cheating at. “Cheating” implies a set of rules. If that rule is “you will stay prisoner here,” or “you will let me destroy your life” then yes, I’ll try and cheat.
Sorry, boring answer but it’s hard to say outside of a context.

4) If you could read the mind of someone famous, who would it be?

Probably a major politician to see what the discrepency is between what they claim to believe in and what they really think, between what they says their reasons are for their actions, and what the real reasons are. Might be a bit depressing though.