A: Psychic phenomena entails to essentially overlaying the Immaterium on physical reality and controlling what happens through force of will. Anyone that can do it consistently is a "pysker", and species have a varying level of psychic potential. Some, such as the Eldar, are invariably powerful psykers, so much so that much of their technology depends on it, some have limited psychic potential but individuals who are capable of matching or even surpassing more attuned species, such as Mankind, and a few, due to the circumstances of their evolution or pecularities individual to that species, have no psychic potential at all and must make do with material means, such as the Tau and ultimately, your species. The
Q'Orl are notable in that they don't have psychic potential, but are able to traverse the Warp and maintain an empire bsubjugating the psykers of other species.
Reality warping is almost entirely Warp-affiliated, though the
C'tan were able to do so through means that bore no relation to the Warp and the
Necrons possessed technology that was capable of not only replicating their feats, but shattering and binding them into fractions of their former selves. Barring extreme technological advancement, this sort of pseudo-psychic phenomena is beyond the grasp of your appendages. Even so, as wierd and the Terran biosphere demonstrate, there is a massive amount that can be done without deviating from the material. Determining the biosphere's prevalent form of reproduction is going to be the next question and that kind of age-stratified dichotomy is more than possible. Anything that isn't outright supernatural in on the table for communication purposes, LEDs aren't only a novel idea, they're more than doable from silicon. Other possibilities are the exchange of electric pulses, vibrating at specific frequencies, or as already mentioned, even radio.