Summary of passage: Isaiah has a vision of the Lord seated on his throne with seraphs hovering overhead, singing to one another, and singing so loudly that the temple shakes and is filled with smoke.
3) Isaiah wants to draw attention to that particular time.
4a) God sitting on a throne, His robe filling the temple, seraphs hovering above with booming voices and creating smoke.
5) Personal question. My answer: He is pure, righteous, reverent, sinless, Almighty, above all else
6a) Earthquakes and smoke
b) Exodus 19:18 Mount Sinai was covered with smoke, because the Lord descended on it in fire. The smoke billowed up from it like smoke from a furnace, the whole mountain trembled violently.
Revelations 15:8 And the temple was filled with smoke from the glory of God and from his power, and no one could enter the temple until the seven plagues of the seven angels were completed.
Conclusions: I think Isaiah is describing what he saw before God speaks to him.