1)
What is the meaning of "Asher Lukach Lach"?
1.
Rashi: It was stolen from you. We find like this - "Ishah Atzurah Lanu" (Shmuel 1:21:6) means [she is withheld] from us.
2)
What is the meaning of "v'At Alis"?
1.
Rashi: You cursed the thief, and I heard the curse. Malbim - she said that she suspects him; the curse was to induce him to return it.
3)
How did Michayhu have the money?
1.
Rashi: He now admitted that he had stolen it.
4)
Why did she say "Baruch Bnei la'Shem"?
1.
Malbim: The curse was only as long as the thief has the money. Now that you returned it, you ceased to be cursed, and you are blessed.