let's start with the "new heavens and the new earth." I have read that Pret's believe this refers to the new covenant in Heb 8. Is this true (yes or no)
Yes. "Heavens and earth" is a Hebrew idiom for the Temple, which represented the Old Covenant and all it entailed (references to the Temple and its practices are found throughout the book of Hebrews). So "new heavens and new earth" would refer to this new covenant and Temple. First, a little background.
The Temple was the dwelling place of God on earth. It was patterned after the Tabernacle which Moses was told to build. (That Tabernacle was patterned exactly after the heavenly Tabernacle.) The Temple as the dwelling place of God on earth is found through the Old testament.
{1} Then King David said to the entire assembly, "My son Solomon, whom alone God has chosen, is still young and inexperienced and the work is great;
for the temple is not for man, but for the LORD God.
1 Chronicles 29:1 (NASB)
{7} Let us go into His dwelling place;
Let us worship at His footstool. {8} Arise, O LORD, to Your resting place, You and the ark of Your strength.
{9} Let Your priests be clothed with righteousness, And let Your godly ones sing for joy.
Psalm 132:7-9 (NASB)
The Law of Moses (also known as the Old Covenant) called for this dwelling place of God on earth.
{8} "
Let them construct a sanctuary for Me, that I may dwell among them. {9} "According to all that I am going to show you,
as the pattern of the tabernacle and the pattern of all its furniture, just so you shall construct it. Exodus 25:8-9 (NASB)
So from the time of the exodus from Egypt until the Temple's first desolation by the Babylonians (586 BC, a span of some 600 years) Israel's religious, cultural, and national identity was tied to the Tabernacle and later to the Temple.
The phrase "heaven and earth" was an idiom that reflected the closeness the people felt with God through the Temple. It was - again - the place where heaven and earth were united: the place where God's presence - His glory - rested.
The purpose of the New Covenant - essentially - was this: to put the Spirit of God
in us: believing Jew and Gentile alike.
We are now the Temple of God: the place where God's glory (His presence) dwells on earth.
{16} Do you not know that you are a temple of God and that the Spirit of God dwells in you? 1 Corinthians 3:16 (NASB)
{19} Or do you not know that
your body is a temple of the Holy Spirit who is in you, whom you have from God, and that you are not your own?
1 Corinthians 6:19 (NASB)
{16} Or what agreement has the temple of God with idols?
For we are the temple of the living God; just as God said, "I WILL DWELL IN THEM AND WALK AMONG THEM; AND I WILL BE THEIR GOD, AND THEY SHALL BE MY PEOPLE.
2 Corinthians 6:16 (NASB)
{19} So then you are no longer strangers and aliens,
but you are fellow citizens with the saints, and are of God's household,
{20} having been built on the foundation of the apostles and prophets, Christ Jesus Himself being the corner
stone, {21} in whom the whole building, being fitted together,
is growing into a holy temple in the Lord, {22} in whom you also are being built together into a dwelling of God in the Spirit.
Ephesians 2:19-22 (NASB)
Christ's sacrifice was to cleanse us of sin before God's presence could indwell us, as is illustrated here:
{15} They assembled their brothers, consecrated themselves,
and went in to cleanse the house of the LORD, according to the commandment of the king by the words of the LORD.
{16} So the priests went in to the inner part of the house of the LORD to cleanse it, and every unclean thing which they found in the temple of the LORD they brought out to the court of the house of the LORD. Then the Levites received
it to carry out to the Kidron valley.
2 Chronicles 29:15-16 (NASB)
The writer of Hebrews is using the work of the Temple priests and Levites to describe the on-going work of the ascended, glorified Christ in heaven, as the work of the earthly priesthood was a foreshadow of God's redemptive plan through Christ.
The glory of the Lord - His very presence - no longer rests in Temples built by human hands. His Spirit rests in us. That's one of the most important distinctions that must be made between the Old and New Covenants.
Now, just to keep this in the spirit of end time discussions, futurists and dispensationalists look forward to a new Temple (third Temple) being built in Jerusalem into which the "Antichrist" will enter and profane by his presence and self-exaltation. But here's the problem: if God's glory no longer rests in a physical structure in Jerusalem, how can a third Temple be holy? And if it isn't holy, how can it be profaned?
The only way for this to happen is if God were to abrogate the covenant of Christ's sacrifice.
There is nothing in the New Testament that says God will return to a system of animal sacrifice to cleanse us from sin. In fact, the writer of Hebrews tells us time and time again about the superiority of Christ's sacrifice over the blood of bulls and goats. There is no justification in scripture for the belief that a third Temple will be raised in Jerusalem, and even if it is, God's presence will not dwell there.
He dwells in us, His church composed of believing Jews and Gentiles.