"Please tell me how you discern Christ's voice from that of your conscience. How does it sound different to you?"
Way too long an answer for that little comment box, so I will address here it before moving on to questions 2 and 3.
I am not so certain about what conscience is.
I look at it as a part of my cultural conditioning that governs morals and ethics, as an orientation within the social, political and religious consensus in which I live. The abstraction I call "conscience" seems to work to keep me within that consensus when I am tempted or urged to act outside of it.
The culture that conditions conscience is the collection of norms a group has adopted to accomplish the universal activities that fulfill human needs. Eating, staying warm, reproducing and resolving disputes are examples of these universal activities. Everyone, everywhere, at all times, has done these things in an amazing array of ways. Conscience is the part of those norms, in a given time and place, that focuses on moral and ethical behavior.
Such consensus, and therefore conscience, always contains exceptions to its rules and, along with flexibility necessary to meet complex situations, these exceptions create the possibility for rationalizing in the matter of morality. That makes conscience vulnerable to sinful states of mind (greed, anger, pride, lust and so on) and an actual accomplice in breaking through its own moral limitations. After all, for every cliche--or love song--that we can hang our hat on as we make a decision, there is another that counsels us to do exactly the opposite. In other words, we can corrupt conscience, or allow others, especially authority figures, to corrupt it for us.
Conscience is also vulnerable to the limitations of the group's knowledge. Even in the most loving states of mind our moral and ethical direction from our conscience can bring us to a bad end for lack of data or information that, if we had the benefit of its possession, we might have been able to choose better. Notions about race and sex and sexual orientation are examples of how conscience is misled, even sometimes without malice, by the definition of "reality" that exists--or is accepted--by a group.
It seems helpful, to me, to think of conscience a belonging to to realm of "the powers"--those institutions--including religion--that are said in some theologies to hold the world together in its fallen condition. (I realize that sentence is packed with notions--all theologies are--but it may (or may not) help communicate how I think about conscience. I certainly do not lean on that--or any other--theology to add validity to what I am saying, just to illustrate it).
My discernment allows Christ to push conscience aside (Christ has defeated the powers, it is written) and leads me to act outside of the consensus of my cultural conditioning (there is one, in effect, that can speak to my conditioning), or to do things included within that consensus but not taken seriously by most of its members.
So, with that said, discerning Christ's "voice" from that of my conscience seems to be a function of three things: the amount of pressure brought to bear on me by the visitation, persistance of that pressure and my experience with Christ and the various other "voices" out there, in the past.
When confronted by a choice, or when I start hearing myself taken to task about something, I know it's Christ when the amount of discomfort or suffering associated with the confrontation causes me is great and becomes greater over time.
The second hall mark of a "visitation" is its persistence. If one of my normal rationalizations or a countervailing cliche does not cause the pressure to dissipate then it's probably Christ. (Sometimes my powers of rationalization have been able to dismiss Christ, but only temporarily. I can crucify Christ, sometimes, and lock It in the tomb of my heart, but when it's Christ I am dealing with I soon hear the rock rolling aside and know that It's back.)
The third discerning factor is my experience. As scary, and humbling, as it has been, at times, following high pressure, persistent urgings has led to good outcomes for me, not only in regard to the situation at hand but also improving my overall condition and ability to function in the future. Like others, I have seen my condition portrayed in the Bible, and elsewhere. For me seeing the Fruits of the Spirit, described in Galatians 5, is validation of good discernment. The five testimonies, a restatement of those Fruits, is another set of benchmarks--as is being led to those green pastures and still waters, notwithstanding what I had to go through to get there.
If I am being visited about something that sounds familiar--something about which I have been visited in the past (shocking that there should be backsliding, I know) or something similar to the subject of a previous visitation then it's easy for me to discern who it is knocking on my spiritual chamber door.
This thing about conscience, though, becomes difficult for me, at this point. I begin to suspect that "mere conscience"--as a pure manifestation of cultural conditioning and a product of secular or religious (second hand) reasoning--is changed, or shaped or conformed or made peculiar when I respond to Christ's visitation. Perhaps it's just that conscience is an abstraction, but the accumulation of wisdom from Christ's leadings and that from conscience seem to have less a bright line boundary than once they did. Again, that may be because in reality there is no such "thing" as a conscience, it's just a notion. It may also be helpful, though, to conceptualize the "conscience" as changed by visitation and so no longer representing just the conditioning by one's culture but, rather, a conditioning--a transformation--by God or Christ or the Holy Spirit. The conscience may, then, become a vehicle for transmission of Christ's wisdom rather than just the wisdom of this group of people, at this time, in this place.
I seem to recall that in the literature of early Quakers the clear communication that The Light was not conscience (which seemed to be cast as a function of reason in Enlightenment thinking). But I think that alongside that clear distinction between the Light and conscience was that idea, in some writings, that The Light could inform conscience as I speculate, here, that it might.
The short answer to your question is that if what I hear makes me uncomfortable enough, and lasts long enough, then I discern it to be Christ and follow it. I can't recall a time when, dragged around like that, it turned out not to be.
In addition, I strongly suspect it's Christ when I am hearing, again, about something I've been called on, before, and, in dealing with it, previously, my condition was improved.