tlong,
You wrote:Where does it say they were added to saved Isreal? Are we not talking about being added to the kingdom which in fact is the Church?
It doesn't say saved Israel. They were added to the ecclesia in Jerusalem made up of the saved in Israel. They were Jews and proselytes who kept the law of Moses and who looked for salvation into God's kingdom on earth.
Today, we don't approach God through the nation of Israel. We don't look for salvation into life in the terrestrial domain like Peter did. We will live mostly in the celestial domain. The kingdom of God will exist in both of these domains as one kingdom.
You wrote:Matthew 3:2
" Repent, for the kingdom of heaven is at hand."
The kingdom of heaven on earth was near and would have come about, if Israel had complied with God's instruction to hear his son, Jesus. Israel did not comply and consequently they were ejected from the Land.
You wrote:Matthew 16:28
"Truly I say to you, there are some of those who are standing here who will not taste death until they see the Son of Man coming in His kingdom."
This occurred when some of Jesus' disciples saw a vision of the future when they were with Jesus on a mountain. The account of this immediately follows the reference you gave.
You wrote:Acts 8:12
But when they believed Philip preaching the good news about the kingdom of God and the name of Jesus Christ, they were being baptized, men and women alike[ when the kingdom was preached]
The Samaritans were baptized during the period in which the gospel of the kingdom (terrestrial) was still being preached.
You wrote:The kingdom has come and if it is not his church, then what is it?
God's kingdom is wherever the authority of his son is recognised. Eventually Jesus' authority will be universally established when all God's enemies are reconciled to Him through the blood of the cross of Christ. (Col 1:20)
Paul