I'll assume you're looking for a simple answer. The simple answer is yes, you're right. The passage in question contains at least one common, garden variety metaphor:
...my memory has a smelltrack...
"Smelltrack" is metaphorically used, and is in a metaphorical construction. The author did not say, for example, "...my memory has a facility like a smelltrack..." or "...my memory recalls smells as if following a smelltrack", and (almost) certainly the author's memory does not have a literal smelltrack.
I did not take the time to analyze the quoted passage thoroughly for other simple metaphors, but many other less simple metaphors do exist in the passage you quoted. Describing those metaphors in detail, however, would begin to complicate the simple answer immediately.
For an example outside the quoted work, but which is illustrative of the issues, consider the word 'metaphor' itself. The word can be regarded as a 'dead metaphor': etymologically, 'metaphor' came from Greek roots meaning 'to bear, carry' and 'along with'. From those roots used metaphorically, the contemporary sense of 'metaphor' derives.
You can see why some people think that language is itself, by nature, metaphorical: all words are popularly supposed to stand for something else. What words 'carry along' with them is presumed (sometimes) to be meaning. In this sense, 'metaphor' in language is inescapable.
Edit: To clarify, in the phrase
my memory has a smelltrack which is like a soundtrack
the simile is "a smelltrack is like a soundtrack", while the metaphor is "memory has a smelltrack". That a simile follows the metaphor does not make the metaphor a simile.
Best Answer
As the example above shows, the prepositions "like" and "as" are not limited to forming similes. They have literal use.
There is nothing that prevents the literal, ordinary use of such preposition within an extended metaphor:
Without context, your third example doesn't manage to establish a metaphor. In the context of a fantasy (say, one in which wizards can change shape or ghosts can possess animals) the statement can be easily taken as purely literal. In a more prosaic context, it can be read as the sort of explicit comparison known as a simile.
We use "metaphor" to mean an implicit figurative comparison. We use "simile" to mean an explicit figurative comparison. This means that you cannot use the word "as" to establish a metaphor. When it establishes a comparison, that comparison is explicit. When it does not establish the comparison, that comparison may be implicit and therefore may be a metaphor.
That the words "like" and "as" establish similes is a good rule of thumb, but it's not a law of nature. "He eats in the manner of a bird" or "She sleeps the way a cat does" manage to stand as similes without using those magic words. The notion that similes use "like" and "as" is much like the notion that nouns are people, places and things -- a reasonable approximation when you're first learning to identify them, but an approximation that you're expected to leave behind once you gain a deeper understanding.