Should we use the Hebrew name for God, YHWH (Yahweh), out of respect for Him, since it’s used in the Old Testament?
Yes, what translates into English as YHWH is the revealed name of God. There are no vowels in the Hebrew, so it is usually spelled as you did, Yahweh. There is much debate about whether to use that name, going back to the fact that it has long been the practice of Jews not to speak it. But it is revealed in Scripture and repeatedly used of God, and I am in favor of Christians using it if they are so inclined.