1)
Does "Ki" give the reason?
1.
Rashi: Yes. Because they made many Mizbechos for sin, I subdued them via the burden of Melech Sarim (10).
2)
Why is there a Sheva under the Beis in "Mizbechos"?
1.
Radak: It is Samuch. Perhaps the word to which it is Samuch (Agalim or Atzavim?) is omitted. We find Mizbechos with a Sheva when it is specified, e.g. "Hirbah la'Mizbechos" (10:1). It says Hirbah because they did more than their fathers, e.g. Achav added Ba'al and Asherah. Why did he need to add? He already had [idolatries]! Rather, he added to his sin.
3)
Why does it say "Lachato" twice?
1.
Radak, from Targum Yonasan: The first is to make others sin. The latter is for a stumbling block.
