Yes but said verses do not necessarily mention a disinclusion of all other saints.
Yes, it is implied by the language used unless there is another verse or passage suggesting otherwise. For example: It would be like saying: All the green marbles are to only be present for the week, and the rest of the other colored marbles will not be seen again until after the week is finished.
Only two people groups are mentioned as going through the Millennium.
"And I saw thrones, and they sat upon them, and judgment was given unto them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years." (Revelation 20:4).
People group #1. They that sat upon the thrones and judgment was given to them.
People group #2. The souls of them that were beheaded for the witness of Jesus, the Word of God, and they did not worship the beast, neither his imagine, and neither did they receive his mark upon their foreheads, or in their hands.
Usually, when you specify something it is for a purpose or reason. If all believers would be included it would have said so.
Also, the next verse says this:
"But the rest of the dead lived not again until the thousand years were finished. This is the first resurrection." (Revelation 20:5).
Please take note that the REST of the dead that lives AFTER the thousand years is STILL REFERRED as the FIRST RESURRECTION. See verse 5 above.
Also, verse 6 says this about the 1st resurrection:
"Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power,..." (Revelation 20:6).
So the 1st resurrection, is not a resurrection of the damned or the wicked. Granted, there will be a resurrection of the wicked, but that comes after the 1st resurrection.
You said:
To me it makes less sense that those who converted during the tribulation would be given power to rule and reign alongside Christ during the MK while those who came to faith before this period would simply be relegated to having no part in this era.
I would rather stick to what the Word of God says in it's most plainest meaning instead.