1) Reverence basically. Not much else to say to be honest.
2) I can't think how to explain this in technical terms at the moment, but basically the Mass is said to God, not the people. It's the priest and God, not the priest, community and God. That's why you don't see responses, although a small minority do a dialogue Mass, which is of questionable vintage (it's a complex issue that I doubt if could get into in much detail) and I'd rather avoid. The readings are there as part of the ritual and prayer. Usually they'll do the English readings afterwards, but I've been to no-frills low Masses where they don't. The 65 transitional Missal had vernacular-only readings if I recall.
3) Because those are words meant for God, and it preserves the sense of mystery in doing so. The Council of Trent actually condemned people in the West who insisted the Canon be had to be said out loud. Only the priest can confect the Sacrament, so there's little point in saying it out loud, at least in the Latin rite. The New Mass, as usual, gets things backwards and (usually) it is said aloud; that comes from the 60's 'community theology' fad. We all had to be a part of it, and saying silent prayers was exclusive an elitist and so on. Follow in a hand missal, say a rosary silently, etc etc.
Occasionally, you might run across a conservative Novus Ordo parish that says the New Mass in Latin with a silent Canon, but be careful not to confuse the two. Language and posture aside, they actually don't have much in common outside of some skeletal elements, Kyrie, Gloria, and such. Daily saint prayers are subtly (or even radically) different, new canons, the Introit's gone, the prayers of sacrifice mostly stripped away, Last Gospel's gone, etc etc etc.
Now comes the part where people come in and say what a bad person I am.