You raise many issues which probably are too large to be treated on this site. It is a large study you are proposing with many side issues.
Let me address one single thing which is extremely important because it has bearing on all the others.
What were the terms of the Law Covenant with Israel -- was it unconditional, or was it strictly conditional? What does Holy Scripture say about that question?
Exodus 19:
5 >>>Now therefore, if ye will obey my voice indeed, and keep my covenant, then ye shall be mine own possession from among all peoples: <<<
for all the earth is mine: 6 and ye shall be unto me a kingdom of priests, and a holy nation. These are the words which thou shalt speak unto the children of Israel.
What would happen if Israel became disobedient?
Deuteronomy 28:
15 But it shall come to pass, if thou wilt not hearken unto the voice of Jehovah thy God, to observe to do all his commandments and his statutes which I command thee this day, that all these curses shall come upon thee, and overtake thee. . .
>>> until thou be destroyed, and until thou perish quickly; because of the evil of thy doings, whereby thou hast forsaken me. <<< . . .
>>> until thou be destroyed. <<< . . .
etc.
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We can see that the law covenant was a bilateral one. Israel had to be obedient for it to function. They would be destroyed if they didn't obey. Once destroyed the covenant obviously became void in their regard. This would include all the things you refer to. Israel ceased to exist as a nation in the remote past. This was God's own judgment; it meant that the covenant had been broken.
Because of the disobedience of Israel, the Psalms, Jeremiah, Isaiah prophesied about a new covenant, a different priesthood. Once we say new, it means that the old is no more. (If you want the scriptures, ask)
This new covenant is what spiritual Israel is under. In this sense, God still has a covenant people but that is not limited to fleshly descendants of Israel.
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Edit: Too bad you don't permit contact.
You made this claim:
Quote: ". The Priesthood itself is described as an eternal covenant in Numbers 25:12,13 "
That is not correct. If you look at that chapter you'll see this:
"11 Phinehas, the son of Eleazar, the son of Aaron the priest, hath turned my wrath away from the children of Israel, in that he was jealous with my jealousy among them, so that I consumed not the children of Israel in my jealousy . . .13 and it shall be unto him, and to his seed after him, the covenant of an everlasting priesthood; because he was jealous for his God, and made atonement for the children of Israel."
This was not with Israel, but with Phineas and his progeny.
When you consider your points about covenants about and them being eternal, you have to consider the main covenant, or contract.
All of the covenants depended upon the Israelites being under the Law Covenant. It was insofar as the Israelites being under the Law covenant "perpetual" for as long as the Israelites were God's people. Thus as pointed out previously, if the Israelites broke the covenant so that they were rejected as God's people and so that their covenant with God became void, all the other covenants you quote would naturally also be voided.
If you look in Psalms, the signs that this would happen already were given early. Here we read:
Ps 110:
2 Jehovah will send forth the rod of thy strength out of Zion: Rule thou in the midst of thine enemies. 3 Thy people offer themselves willingly In the day of thy power, in holy array: Out of the womb of the morning Thou hast the dew of thy youth. 4 Jehovah hath sworn, and will not repent: Thou art a priest for ever After the order of Melchizedek.
Ps 2:
6 Yet I have set my king Upon my holy hill of Zion.
7 I will tell of the decree: Jehovah said unto me, Thou art my son; This day have I begotten thee. 8 Ask of me, and I will give thee the nations for thine inheritance, And the uttermost parts of the earth for thy possession. 9 Thou shalt break them with a rod of iron; Thou shalt dash them in pieces like a potter’s vessel.
10 Now therefore be wise, O ye kings: Be instructed, ye judges of the earth. 11 Serve Jehovah with fear, And rejoice with trembling. 12 Kiss the son, lest he be angry, and ye perish in the way, For his wrath will soon be kindled. Blessed are all they that take refuge in him.
Gen 49:
. 9 Judah is a lion’s whelp; From the prey, my son, thou art gone up: He stooped down, he couched as a lion, And as a lioness; who shall rouse him up? 10 The sceptre shall not depart from Judah, Nor the ruler’s staff from between his feet, Until Shiloh come; And unto him shall the obedience of the peoples be. 11 Binding his foal unto the vine, And his ***’s colt unto the choice vine; He hath washed his garments in wine, And his vesture in the blood of grapes: 12 His eyes shall be red with wine, And his teeth white with milk.
In the above we see that Judah is promised that Messiah would come from his tribe. It is on David's throne he would be established. He from the tribe of Judah would become a priest according to the manner of Melchizedek.
This by necessity meant a change of law because only the Levites were permitted to be priests under the Law Covenant.
That is what Jeremiah spoke of here:
Jeremiah 31:31:
Behold, the days come, saith Jehovah, that I will make a new covenant with the house of Israel, and with the house of Judah:
Having said that a new covnenant would come, the old would naturally be replaced by that new one.
This is what is preached in the NT.
But as also stated your material and subject is way too large for this one posting and you do not permit a personal approach.