1)
What is the addition that Hashem's eyes will be open to their supplications? Verse 49 already said that Hashem will heed their prayer from Chutz la'Aretz!
1.
Malbim: This is even if they do not face the Bayis.
2)
What is "b'Chol Kar'am Elecha"?
1.
Radak: Whenever they call to You amidst their affliction and return to You. The same applies to "ka'Shem Elokeinu b'Chol Kar'einu Elav" (Devarim 4:7) - in Teshuvah.
