1 Corinthians 13: 9-12 (KJV)
9 For we know in part, and we prophesy in part.
10 But when that which is perfect is come, then that which is in part shall be done away.
11 When I was a child, I spake as a child, I understood as a child, I thought as a child: but when I became a man, I put away childish things.
12 For now we see through a glass, darkly; but then face to face: now I know in part; but then shall I know even as also I am known.
By reading contextually, we can understand these verses and phrases easily. Looking at the context clues, each verse gives the answer to the above mentioned questions.
Verse 10 contrasts "that which is perfect" against "that which is in part." When the perfect comes, the imperfect will vanish. To know to which "perfect" the writer refers to, we should also know that which he labels as imperfect or "in part." And the latter is easier to determine than the former. Reading verse 9 (and verse 8), we can resolve that the writer was referring to the believers' knowledge (that time) as imperfect and incomplete. They did not know everything;
"8 Charity never faileth: but whether there be prophecies, they shall fail; whether there be tongues, they shall cease; whether there be knowledge, it shall vanish away. 9 For we know in part, and we prophesy in part."
But the writer believed that the time of perfection will come when the believers will know completely, and partial knowledge will be a thing of the past.
"10 But when that which is perfect is come, then that which is in part shall be done away. 11 When I was a child, I spake as a child, I understood as a child, I thought as a child: but when I became a man, I put away childish things. 12 For now we see through a glass, darkly; but then face to face: now I know in part; but then shall I know even as also I am known."
This understanding of verse 10 is connected to verse 12 with the phrase "face to face". When the perfect knowledge comes and everything is known to the believers, the believers will not "see through a glass, darkly" but will see things clearly and directly just like looking at the mirror face to face. There will be nothing hidden. Everything the believers need to know will be known.
But when will this be? Will it be when we are already in heaven with the Lord? Or will it be before?
I strongly believe that it is NOW that "that which is perfect" has come. With the New Covenant written, we, believers, have everything we ought to know. I believe that verse 8 has already been fulfilled. Thus, on this day, there is no more prophecy, no more speaking in unknown languages, and no more special knowledge. Why? Because this time is the only time left before we reach heaven, and these impartial things (that is, prophecy, speaking in unknown languages, and special knowledge) should be gone before three things will remain: hope, faith, and love (verse 13). Right now, we have hope, faith, and love. We don't need hope and faith in heaven because we will be actually where we hope for. And there, we will see and be with God. We will not need faith in heaven. We will already live by sight! This is why the greatest is love because it is the only thing that will stay for eternity- now and forever.
You see, it is very important to learn how to read the context because it, alone, can give you the accurate understanding of passages such as this. When you know how to read the context, you will not need any people commentaries or books to "help" you understand the scriptures. The New Covenant alone is complete and contains the perfect knowledge you need.