This part, I find, is interesting. How does this idea work? Do you see that, according to dispensational theology, heaven is to be brought to earth as in it is 'here' vs. 'out there' somewhere?
Unfortunately when posting a lot on this forum one can easily looses track of what post you are referring to especially after many pages have flown by.
But I'll take a crack at the last part of your question.
I do not consider Heaven to be "out there somewhere" but rather simply in another dimension.
When Jesus was taken "up" to Heaven, for instance, He did not really go up like a helium balloon and then continue in a straight line like a rocket ship until He ended up on the throne of God just outside the far side of the universe.
I know this is probably more than you asked about - but Jesus did not "walk through walls" after His ressurection as some claim. The Holy Spirit did not "arrive" somewhere He was not already in when He "fell" on the disciples in the upper room.
We are talking about changing dimensions for Jesus and relational changes for His Spirit etc. IMO.
God is everywhere present at all times and without division in His attributes or substance. He is Spirit.
I.e. - God is "infinite" and not "finite".
I remember one class I taught many years ago when a particular rather vocal lady who had not really consider anything different than what she had been told as a youth took exception to my telling the class that Heaven wasn't really "up". I mean - she really took exception to my saying that.
My reply to her was that if Heaven was really up (as when Jesus was taken up into Heaven) then people in Australia would have to stand on their heads when they lifted up holy hands to God as the scriptures tell us to do.
But the point is that Heaven (or the New Jerusalem for that matter) "coming down" simply means that the other dimension (or dimensions perhaps) are available to us on earth just as they were to Jesus after the resurrection when He suddenly appeared in their midst or when to His Holy Spirit "came" at Pentecost or when the Holy Spirit "landed" on Jesus at His baptism.
We can well be seated on the throne with Jesus (as the scriptures tell us that we are as believers) and ruling with Him in the "Kingdom of God" in this age (taking authority etc.) and still remain so reigning with Him when the Kingdom of God comes to the earth for 1000 years.
Now that's a long answer to something you may not be asking. But point is that there are many ways to look at these things and black and white isn't necessarily the only one.
Unless the Lord tarries for another couple of thousand years we may soon see through the glass with a bit more clarity.
I for one can hardly wait.