Will the saved people that are in heaven as spirits … ?
That's a big assumption for a general category of Christianity.
Some denominations do believe this doctrine, but many others fail to find any biblical support for it.
Nowhere does the Bible ever say that people will go to Heaven when they die.
The Bible talks about death as "sleep", and teaches that the dead are awaiting resurrection.
A few, the elect, will be resurrected at Jesus's return ("the first resurrection"), while the rest of humanity have to wait until the end of the thousand years ("the second resurrection").
… on earth with Christ for 1,000 years
Again, that's a big assumption for a general category of Christianity.
In this case though, it is one that is supported by a literal reading of the Bible.
The problem is, the denominations that believe the dead go to heaven (possibly via purgatory) and the denominations that believe that Jesus will rule on Earth with the newly resurrected elect for a thousand years, tend not to overlap.
Your problem arises from choosing doctrines from different, conflicting denominations.
That they don't fit together well, or even don't make sense, is to be expected.