> doSomething (->
  > 'hello'), 1

> Indentation is significant in CoffeeScript, just like it is in Python. Just having a parenthesis shouldn't change that.

The point, I think, is that the example above should be an error instead of compiling into something you wouldn't expect.

Here's a syntax I've seen a lot:

  doSomething ->
      'hello'
  ,   1

or even

  doSomething ->
      'hello'
  ,
      1

That style is also handy to construct a long list of object literals.

> This is called destructuring assignment,

I think destructuring assignment is something else entirely. http://coffeescript.org/#destructuring

> its probably better to use isnt instead of !=, although rather than !=, you would want !==

'!=' is equivalent to 'isnt'. And '!==' is not CoffeeScript at all.