What is the meaning of "Ho'el"?
Rashi (from Erchin 16a): Swear [that Elisha sent you]. Malbim - Na'aman was unsure whether or not Elisha sent him.
Why is there is a Sheva under the second Kaf in Kikerim?
Radak: This shows that it is Samuch to "Kesef".
What are "Charitim"?
Rashi citing Menachem: They are kinds of garments and scarves. This is like "veha'Mitpachos veha'Charitim" (Yeshayah 3:22).
Rashi citing Targum Yonasan: Pildasin 1 . In Yeshayah (3:22), he translated it Maskaya (a frame around the womb - Rashi there).
Rashi: They are long wallets tied with drawstrings.
Radak: So Yonason (Shoftim 14:12) translates Sadinim (sheets).
To whose youths did he give?
Rashi: He gave to two of his own youths. Malbim (24) - Na'aman was unsure whether or not Elisha sent him 1 .
Who carried in front of whom?
Rashi: The youths carried in front of Gechazi.