As we may read in one of the first ahadith from Sahih al-Bukhari after the first meeting between Jibreel () and Muhammad (), the mother of believers Khadija () took her hsuband to her cousin Waraqa ibn Naoufal who actually informed him that he has been given a message from the Almighty and also informed him whom he has met, and other things he could tell based on his wisdom of the scripture:

Narrated 'Aisha (the mother of the faithful believers): The commencement of the Divine Inspiration to Allah's Messenger (ﷺ) was in the form of good dreams which came true like bright daylight, and then the love of seclusion was bestowed upon him. He used to go in seclusion in the cave of Hira where he used to worship (Allah alone) continuously for many days before his desire to see his family. He used to take with him the journey food for the stay and then come back to (his wife) Khadija to take his food likewise again till suddenly the Truth descended upon him while he was in the cave of Hira. The angel came to him and asked him to read. The Prophet (ﷺ) replied, "I do not know how to read." The Prophet (ﷺ) added, "The angel caught me (forcefully) and pressed me so hard that I could not bear it any more. He then released me and again asked me to read and I replied, 'I do not know how to read.' Thereupon he caught me again and pressed me a second time till I could not bear it any more. He then released me and again asked me to read but again I replied, 'I do not know how to read (or what shall I read)?' Thereupon he caught me for the third time and pressed me, and then released me and said, 'Read in the name of your Lord, who has created (all that exists), created man from a clot. Read! And your Lord is the Most Generous." (96.1, 96.2, 96.3) Then Allah's Messenger (ﷺ) returned with the Inspiration and with his heart beating severely. Then he went to Khadija bint Khuwailid and said, "Cover me! Cover me!" They covered him till his fear was over and after that he told her everything that had happened and said, "I fear that something may happen to me." Khadija replied, "Never! By Allah, Allah will never disgrace you. You keep good relations with your kith and kin, help the poor and the destitute, serve your guests generously and assist the deserving calamity-afflicted ones." Khadija then accompanied him to her cousin Waraqa bin Naufal bin Asad bin 'Abdul 'Uzza, who, during the pre-Islamic Period became a Christian and used to write the writing with Hebrew letters. He would write from the Gospel in Hebrew as much as Allah wished him to write. He was an old man and had lost his eyesight. Khadija said to Waraqa, "Listen to the story of your nephew, O my cousin!" Waraqa asked, "O my nephew! What have you seen?" Allah's Messenger (ﷺ) described whatever he had seen. Waraqa said, "This is the same one who keeps the secrets (angel Gabriel) whom Allah had sent to Moses. I wish I were young and could live up to the time when your people would turn you out." Allah's Messenger (ﷺ) asked, "Will they drive me out?" Waraqa replied in the affirmative and said, "Anyone (man) who came with something similar to what you have brought was treated with hostility; and if I should remain alive till the day when you will be turned out then I would support you strongly." But after a few days Waraqa died and the Divine Inspiration was also paused for a while.
(Sahih al-Bukhari and Sahih Muslim)

So the prophet() didn't know what or whom he has met and was frightened as we can see in the hadith above and other likewise narrations.

See also a shorter version in Sahih al-Bukhari and a longer version in Sahih al-Bukahri too.

The hilarious part in this is that Muhammad DID admit that Satan told him revelations once, and neither he nor his followers couldn't distinguish it until he got another revelation. I don't believe it either way though.

The text in question makes no mention of anyone called Jesus.

The angel Gabriel is speaking to Zacharias, telling him that his aged wife Elizabeth will give birth to a son who will be called John. Gabriel specifically speaks of the baby yet to be conceived as destined in the will of God to “be great in the sight of the Lord”. This is the Greek word kyrios, but context is totally unambiguous that this Lord is the Lord God of Israel. John will be great in the sight of Israel’s Lord and God.

Gabriel continues to say that John will be filled with the Holy Spirit of God, even from his mother’s womb, and that he shall turn many in Israel to their God the Lord.

It is not until Elizabeth is six months pregnant that Gabriel speaks again in the written record, being sent to the virgin Mary, and this is the first time the name ‘Jesus’ is spoken by him. This is in verse 31 of that same first chapter of Luke, when he tells Mary that the Holy One to be born will be called Jesus, and also be called the Son of the Highest.

Jesus is described as coming for the first time in Hebrews 9:26 – and Gabriel appropriately only names the one whom John the Baptist was to prepare the way for at the announcement of Mary’s miraculous conception of this Jesus. It is significant that Jesus himself, as an adult, said that John the Baptist was the fulfilment of the prophecy about the Elijah to come (Matthew 11:14 & 17:12 cf. Malachi 4:5). This is where the penny should drop. Malachi foretold one coming to do a work of preparation for the Lord God of Israel. Jesus showed that John the Baptist, who prepared the way before him, was the fulfilment of that prophecy. John the Baptist himself agreed with that – John 1:19-27 – saying he was preparing the way for the Lord, the Lord who came after him, whose laces he was not worthy to untie.

To answer the question then: The significance of what Gabriel said in Luke 1:15-17a was fully known to him, without him ever mentioning Jesus. When he did mention the coming of Jesus, many months later, he also knew then how John would fulfil the prophecies, but he did not spell that out. It was Zacharias who, in the second text of the question, gave the meaning, saying of his son, “And thou, child, shalt be called the prophet of the Highest: for thou shalt go before the face of the Lord to prepare his ways” (Luke 1:76 KJV). Gabriel said in Luke 1:31 that Jesus would also be “called the Son of the Highest”.

Gabriel understood that John was the prophet of the Highest (the Lord God of Israel), and that Jesus, being Son of the Highest, would have John prepare his way for him.

Jesus himself explained the significance of John, who went before him to prepare people for the Messiah, also called kyrios. It is for those who have been prepared for Messiah, and who have received him as their Saviour and their Lord, to let the scriptures speak to them by the teaching of the Holy Spirit. John turned many in Israel to their God the Lord by turning them to Jesus Christ as their Saviour and their Lord. The one whom the 'children of Israel' followed prior to the coming of Jesus into the world was, indeed, this Lord God of Israel. To turn to the Lord Jesus in the way Gabriel said is to turn to the Lord God of Israel.

What violence? The prophet wasn’t harmed, he was shocked and got scared. Plus Wasn’t Paul blinded by the vision he saw? What about this? He was harmed. Or is that Jesus so it’s okay? And what does the first verses revealed say? Isn’t that what you would expect from God? Read in the name of your Lord, who has created (all that exists) has created man from a clot. Read! And your Lord is the Most Generous Angel Gabriel is mentioned in many places in the Quran and Hadiths, Surah 2:97 directly says that Gabriel revealed the Quran to the prophet, i don’t understand the problem.