No...Googlebot reads from left to write and the most left word is valued more than anything right of it.
For a specific search like "one two three" - not likely. But Google seems to keep it pretty much in order, and close, for the first cut of the action.
Depends on the match type used, in your example "one two three" is an exact match (keywords within "") so your advert would only appear if those words were searched for in that order e.g. Search: one two three four, would not trigger your advert and neither would two one three.
Quotes = Phrase Match, not Exact Match. But you're still right about the order being important - that's true for Phrase and Exact Match. For Broad Match, since the Quality Score will vary for different search queries, the results will be different, though the advert may well appear for exactly the same searches (or not - nobody fully understands the Broad/Expanded Matching process - do they?)