Hi there Eugene, The answer to your first question is no.
1Pe 4:12 Beloved, think it not strange concerning the fiery trial which is to try you, as though some strange thing happened unto you:
1Pe 4:13 But rejoice, inasmuch as ye are partakers of Christ's sufferings; that, when his glory shall be revealed, ye may be glad also with exceeding joy.
1Pe 4:14 If ye be reproached for the name of Christ, happy are ye; for the spirit of glory and of God resteth upon you: on their part he is evil spoken of, but on your part he is glorified.
1Pe 4:15 But let none of you suffer as a murderer, or as a thief, or as an evildoer, or as a busybody in other men's matters.
1Pe 4:16 Yet if any man suffer as a Christian, let him not be ashamed; but let him glorify God on this behalf.
1Pe 4:17 For the time is come that judgment must begin at the house of God: and if it first begin at us, what shall the end be of them that obey not the gospel of God?
Obviously those who come out of the great tribulation can't be the Church that was tried during the first half of the trib....Your question threw me off with the words "great multitude" I'm assuming you are referring to those who have washed their robs.
During the first half of the trib. all Christians will be tested. During the second half of the trib. Israel will be tested. Two separate groups. I don't see any non-Jew coming out of the trib. saved. Only Israel. They will finally realize that Jesus is their messiah.
As for Rev. 3:10, that is when the end of the first half of the trib comes, all Christians who have been tested and have not apostatized, (religious rebellion) but held fast to their profession of faith, will be gathered to the Lord by the power of the Holy Spirit. He (Holy Spirit) will gather up the victorious believers and with Himself go to Jesus, who, I suppose, will present us to His Father as His glorious Church....I like 1 Peter 4:17 because I think it explains the purpose of the first half of the trib. in that judgment must begin during the first half of the trib. with the Church to reveal who is really Jesus' Church. Because the Holy Spirit takes us up to be the the Lord, He will not come back on the earth.