So grace is not good news? How can there be a separate "gospel period" and "grace period"?
Absolutely.
Taking scripture completely out of its context. That Psalm is specially about King David and not you.
So that "good news" (i.e., gospel) was not in the "gospel period"?
Are you unaware that the sign gifts ceased even before the end of Paul's ministry?
Paul, who had performed even "special miracles" that healed people with a handkerchief, and yet was later leaving his friend sick and recommending wine as medicine. See Acts 19:11-12, 2 Tim 4:20, 1 Tim 5:23
And yet so much of this "good news" (i.e., gospel) is outside of the "gospel period".
Is there a point?
And yet God separated Israel from the rest of the world.
No, the "birthday of the church" was not on a lawfully required feast day for Israel. Peter preached to ISRAEL on that day, and not to the body of Christ. Acts 2:22
He was here to fulfill the law AND the prophets AND the psalms. It was NOT specially about His fulfilling the law.
So nice.
It's really too bad that you cannot see the truth that God gave Paul revelation what was hidden until He revealed them to Paul. This is the primary source of your confusion.