1)
Does "Ki" give the reason?
1.
Rashi: Yes. Because he prepared his heart, he succeeded.
2.
Malbim: Hashem's Hashgachah brought him here in the merit of Torah like I explained (6, that Ezra founded the pillar of Torah).
2)
For what did he prepare his heart?
1.
Malbim: For three things - to expound Toras Hashem, to do (for action is primary, and not expounding), and to teach Chok and Mishpat to Yisrael.
