Grace (not law) unto you, and peace,
from God our Father and the Lord Jesus Christ.
Your first statment referring to Hebrews 10:16 needs both correction and clarification. Let's quote it exactly from the Bible, and then note some spiritual insights about it:
"This [is] the covenant that I will make with them after those days, saith the Lord, I will put my laws into their hearts, and in their minds will I write them"
Insights on Heb 10:16
1. Heb 10:9 just previously told us to take away law (first) to establish grace (second); And because they are contrary things that cannot co-exist in peace. So let's apply such to everything forward from Heb 10:9.
2. Notice the word new is NOT in this verse as you assumed it was; So it's old of old/new, which is to say law of law/grace. Heb 2 notes give more earnest heed to what's said is how we shall escape. The other option is not escape, snared, and by another law.
3. It's "this" of this/that, so law of law/grace, this world of this world/that world, beneath of beneath/above (from John 8:23)
4. It's for "them" of them/us, law of law/grace, and God hath not appointed us to wrath (law): 1Thess 5:9.
5. It's plural "laws, hearts, minds" = double-minded; And plural is from a plural God, not from God is one.
6. "Will I" is mirrorly reverse of I Will, therefore such is worded as a question, not as a statement.
7. If it's crap (law: dung), then flush it; For any law added to grace makes it no more grace, in the same manner death added to life makes life non eternal. Our goal is to lay hold on eternal life, which is not life after death, but life void of death.
Your second statement referring to 2Corinthians 3:6 also needs correction and clarification. So let's also quote it exact from the Bible:
"Who also hath made us able ministers of the new testament; not of the letter, but of the spirit: for the letter killeth, but the spirit giveth life".
1. It's about the new of old/new testaments... so
2. not of the letter (law), but of the spirit (grace)
3. because the law killeth, but grace giveth life
4. 2Cor3 goes on to compare law glory vs grace glory, as ministration of death vs ministration of life; And when compared, instead of mixed, we are changed from law to grace, as by the Spirit (not by the Ghost)
So in the words of Luke 11:35 "Take heed therefore that the light (grace) which is in thee be not darkness (law)".
Law judges all sinners, none righteous, so all perish by law. A little law is like a little cancer, which can and will kill the whole body if not all removed. So the opertion of God removes all cancer us law.
Grace judges all righteous, sinners none, so none perish by grace, unless you add law, which is like adding death to life, which is a dead end.
Bottom line: If it's crap (dung: law), flush it.
The GRACE of our Lord Jesus Christ WITH YOU ALL. AMEN.