What is the meaning of "Misgodedim"?
Rashi: It is an expression of Seritah (scratching and wounding). Radak - they did so amidst mourning.
Why were they bringing frankincense and a gift for Beis Hashem?
Rashi: They began to go before they heard about the Churban 1 ; they heard on the way to the Bayis 2 . This is why their clothes were torn and their beards were shaven!
Radak: The Churban was in Av. Now it was Tishrei. How can it be that they did not hear beforehand?! (Do not say that they left shortly after the Churban. Shechem and Shilo are in Yosef's portion, which is not so far from Yerushalayim. It is only a few days journey to Yerushalayim! - PF) We can say that they heard that Yerushalayim was conquered and Yisrael were exiled, but they thought that since Nevuzaradan left some people, he left also the Bayis, so the remainder could offer Korbanos there.
Radak: They heard also that Melech Bavel appointed Gedalyah; they were heading towards him.