They were one of a list of the Heavenly Assembly....and Paul is exhorting us to see by faith what lies ahead, where we are going, and those who have already run the race...he is not commending that we communicate with them, but that we know that where they are, where the Angels are etc is where we are headed....Paul is getting us to use our eyes of faith, and not grow weary and take our eyes off the hope before us.
Out of deference to the request, I will only focus on this one. Frankly, you're wrong here. The author of Hebrews is not speaking of what lies ahead, he is speaking of what has already occurred. "You have come", not "You will come"
Hebrews 12:
22 But
you have come to Mount Zion and to the city of the living God, the heavenly Jerusalem, and to innumerable angels in festal gathering,
23 and to the assembly of the first-born who are enrolled in heaven, and to a judge who is God of all, and
to the spirits of just men made perfect,
24 and to Jesus, the mediator of a new covenant, and to the sprinkled blood that speaks more graciously than the blood of Abel.
We have already come to the spirits of just men made perfect. Every time we approach in prayer the throne of grace, the heavenly Jerusalem, we come every bit as much into their presence as we do the angels, God, and Christ.
And while I don't disagree that Paul is the probable author of Hebrews based upon tradition, I am curious why you would accept this extra-Biblical tradition.