Who gets to escape the hour of trial of the Tribulation?

Those who "keep the word of His patience, I also will keep thee from the hour of trial, that hour which is to come upon the whole world, to try them that dwell upon the earth" (Rev. 3.10).

Do all Christians keep the word of His patience? Of course not. Paul says there are carnal and spiritual Christians.

Is this confirmed elsewhere that those who are watchful and prayerful may escape all these things that shall come to pass of the Tribulation?

Yes. "Watch ye therefore, and pray always, that ye may be accounted worthy to escape all these things that shall come to pass, and to stand before the Son of man" (Luke 21.36).

Stand before the Son of Man takes place where?

In 3rd Heaven, they "stood before the throne, and before the Lamb, clothed with white robes, and palms in their hands" (Rev. 7.9). This takes place before even the first trumpet of the Tribulation is blown in Rev. 8.7 when "the first angel sounded."

Those mentioned in 7.9 are overcomers, for (a) the white garments are promised to those in Sardis who have not defiled their garments, (b) not to pass through the trial of the Great Tribulation to come is assured to those in Philadelphia who have kept the word of patience, and (c) the palm is always a symbol of victory. The man child spoken of in 12.5 is likewise an overcomer, since he will rule the nations with a rod of iron.

"And palms in their hands"—This signifies victory (Lev. 23.39-43). During the feast of tabernacles branches of palm trees are used, which feast denotes that God will temporarily dwell with His people (thus typifying the millennial kingdom).

Is there a 3rd verse that supports first rapture before the throne according to readiness?

"Then shall two be in the field; the one shall be taken, and the other left. Two [women shall be] grinding at the mill; the one shall be taken, and the other left. Watch therefore: for ye know not what hour your Lord doth come" (Matt. 24.40-42).

Whose Lord? Believers. One believer will be taken and the other left to pass through the time of testing of the Tribulation. What was the condition for being taken? Being watchful.

Other proofs as follows:

(1) By reading Matthew 24.42 together with 1 Thessalonians 5.2, 4, it is evident that there are at least two raptures: for note that the first passage suggests rapture before the Tribulation because one must be watchful since he does not know when his Lord will come; while the second passage suggests rapture after the Tribulation because one knows when the day of the Lord shall come.

(2) The places to be raptured towards are also different. Whereas Revelation 7.15 mentions to “the throne of God” and Luke 21.36 mentions “to stand before the Son of man”, 1 Thessalonians 4.17 says that it is to “the air” – Such distinctions would thus indicate that the entire body of believers is not raptured all at one time.

(3) Mark 13 states, “But of that day or that hour knoweth no one, not even the angels in heaven, neither the Son, but the Father” (v.32), So that the day of the coming of Christ is unknown. But 1 Thessalonians 4 declares that “the Lord himself shall descend from heaven, with a shout, with the voice of the archangel, and with the trump of God” (v.16). From this second passage we know that the appearing of Christ is after the sounding of the seventh trumpet. And hence the first passage relates to pre-tribulation rapture while the second relates to post-tribulation rapture.