Why does a unique person have a unique perception?
Probably because perception (I assume you mean the subjective phenomenon of qualia) is physically happening somewhere in the brain, and brains are regular physical objects which are as unique as any stone lying somewhere, they don't just switch attributes or identity with others.
If one loses consciousness, why won't there be a random swap to someone elses consciousness?
Why would it?
Why is there a blackout of ones perception in that case,
Because "perceiving" (taking note of things that can be perceived) is what consciousness does, and being unconscious is defined as not being conscious, i.e. not perceiving.
How does time extrinsically pass yet doesn't pass while unconscious, if it requires an observer?
By way of an analogy: if we implement "time" in a computer, the time "perceived" by the computer is simply a big number which counts the numbers of seconds or milliseconds, sometimes nanosecond since an arbitrary time "0" (often defined as "1.1.1970 at 00:00" or "the time the computer was switched on"). The computer has to trust that whatever machinery in itself that counts up that number (at the lowest level some kind of very simple oscillating device, i.e. some kind of quartz oscillator etc.) "keeps time". Which it does because it has been designed just so. But if said oscillator would start misbehaving, i.e. taking 1 second for one "tick", but then 10 seconds for the next, the computer would have no way to notice this. From the point of view of the computer, time would be exactly the same as before - one tick, one second - while in the outside world, time would pass slower or faster.
Imagine the same happens in the brain, just wildly more complicated.
You can experience that yourself - famously, time flies if you're having fun, and time passes incredibly slowly if you're sitting in a boring school classroom. Time perception for us is clearly as relative as time perception to a computer.
If it was material,
What do you mean if it "was" material? There is no objective reason to believe that it is not material.
what quantum of qualia has an electron?
An individual electron does not require to have qualia, i.e. there is no reason to assume that our conscience would perceive individual electrons. A simple reason is that this would bring no evolutionary benefit whatsoever, or Occams Razor (individual electrons do not usually "happen" as an event in nature, as far as individual animals like us are concerned).
If merely signal exchanges between synapses, pericarya and axons form consciousness, what happens in the timespan where the signals don't arrive? Why does one not notice briefest unconsciousness?
That's just the way it is if you stack complex informational systems on top of another. If consciousness is running on our brain like software runs on hardware, then it is completely normal and to be expected that consciousness cannot "see" the workings of the brain itself. Same as no software "sees" the working of the hardware it runs on. (And no, sensors that sense aspects of the hardware, like temperature, voltages etc., do not count - the software does not perceive the hardware it specifically runs on, i.e. the internal hardware registers, MLUs, RAM locations etc.).
If physical data translate to mental data, why do electrons cause pressure, or thought, or pain, if electrons are symmetric?
You would have to formulate this differently, as written the words make no sense whatsoever.
