1)
Why did Chiram send to David?
1.
Malbim: It was to make a Bris with him and build a house for him. Just like David was king over all Yisrael, also nations that he did not know will serve him!
2)
What are "v'Charashei Etz v'Charashei Even Kir"?
1.
Radak citing Targum Yonasan: They are professional wood cutters and stone quarriers and expert architects to build walls.
