1) Begotten means fathered. Jesus is the only-begotten Son of God (Jehovah, according to Psalms 83:18 of the Old King James Version of the Bible) because Jesus is the only one created by God and SOLELY by God. All other creations are created by God's power, but through Jesus.
Colossians 1:13-20--He delivered us from the authority of the darkness and transferred us into the kingdom of the Son of his love, 14) by means of whom we have our release by ransom, the forgiveness of our sins. 15) He is the image of the invisible God, the firstborn of all creation; 16) because by means of him all [other] things were created in the heavens and upon the earth, the things visible and the things invisible, no matter whether they are thrones or lordships or governments or authorities. All [other] things have been created through him and for him. 17) Also, he is before all [other] things and by means of him all [other] things were made to exist, 18) and he is the head of the body, the congregation. He is the beginning, the firstborn from the dead, that he might become the one who is first in all things; 19) because [God] saw good for all fullness to dwell in him, 20) and through him to reconcile again to himself all [other] things by making peace through the blood [he shed] on the torture stake, no matter whether they are the things upon the earth or the things in the heavens.
2) The answer to this one is essentially the same as in the first one. God's power (God's holy spirit, or active force) and planning is what was used to make everything, Jesus is the means by which that work was done (read above in Colossians 1:17). Oh, and just to be sure, we know the above scripture is talking about Jesus because it says in verse 15 that the person being spoken of is the IMAGE of God and the firstborn of all creation.
3) Jesus is not God Himself. Jesus is God's Son. Jesus Himself said so.
John 13:16--Most truly I say to YOU, A slave is not greater than his master, nor is one that is sent forth greater than the one that sent him.
John 5:30--I cannot do a single thing of my own initiative; just as I hear, I judge; and the judgment that I render is righteous, because I seek, not my own will, but the will of him that sent me.
John 14:28--YOU heard that I said to YOU, I am going away and I am coming [back] to YOU. If YOU loved me, YOU would rejoice that I am going my way to the Father, because the Father is greater than I am.
Jesus Himself said it. He said that the one sent is lesser than the one doing the sending, and that Jesus was sent by another. Since there is no one greater than God, and yet there is someone greater than Jesus because Jesus was sent, Jesus cannot be God. Jesus further reiterates that fact by outright saying "the Father is greater than I am."
The reason so many believe that Jesus is God is because they take some scriptures without reading ALL related scriptures. Here's one example.
John 14:9-10--Jesus said to him: “Have I been with YOU men so long a time, and yet, Philip, you have not come to know me? He that has seen me has seen the Father [also]. How is it you say, ‘Show us the Father’? 10) Do you not believe that I am in union with the Father and the Father is in union with me?
Jesus says the two are in union, and many take that to mean a Trinity. But let's read on.
John 17:20-21--I make request, not concerning these only, but also concerning those putting faith in me through their word; 21) in order that they may all be one, just as you, Father, are in union with me and I am in union with you, that they also may be in union with us, in order that the world may believe that you sent me forth.
Is Jesus saying that anyone who follows Him is also God, being that He says that we are ALL in union with the Father and with Jesus? Of course not. Rather, Jesus is saying that we are all aimed at the same goals, all willing to work together in the same plan to attain those goals. THAT is how Jesus and Jehovah are in union, not in a physical same Being, but rather in their goals and plans to attain those goals. Those that follow Jesus also then adopt those same goals and plans, and are also in union with Jesus and Jehovah God.
Jesus is God's Son, but not God Himself. He said so.