Hi Timf, I am not sure I have digested your post but let me at least try to make some comments concerning my reaction.
1) I believe the New Covenant is with both believers who gained approval by faith under the Old Covenant, and with believers whose faith was credited as righteousness under the New Covenant.
2) We can imagine how the future might unfold, and our views might hit close to the mark or not. However, if our understanding of God's word indicates this or that will happen, and this other thing will not happen, it is silly to consider them as possibilities.
3) Yes, I agree everything Jesus said is true, and those who claim He did not actually mean what He said, are simply substituting the truth of God for the clever stories of men.
4) Matthew 24:34 says "Truly I say to you,this generation will not pass away until all these things take place." I do not believe all the things Jesus had been talking about have taken place, even after 2000 years, so was Jesus just kidding? Nope. "Generation" has a range of meanings including a type or kind of people. So believers in Christ will not pass away before the second coming is one potential way of looking to the verse.
5) The great commission was given to born again believers, whether Jew or Gentile, for there is no difference in Christ The line, will be with you always, identifies anyone who has been born again and sealed with the Spirit of Christ.
6) Yes, we are live as Paul lived, expecting Christ's immanent return.
7) The kingdom of heaven that is at hand is our salvation where God transfers us from the realm of darkness into the kingdom of His Son.
8) Yes, the visible church is riddled with tares, just as scripture says. Therefore our outreach should not exclude those who profess faith.
9) When Christ returns, all the unfulfilled promises associated with the Messiah will be fulfilled.
10) I do not see the church as plan B, but rather part of Plan A, God's redemption of His chosen people.