Why did Yehoyachin go out to Melech Bavel?
Rashi: It was to do Melech Bavel's will; it was not for war.
What are "Sarav v'Sarisav"?
Radak citing Targum Yonasan: His officers and Giborim.
How could this be Nebuchadnetzar's eighth year? His first year was Yehoyakim's fourth year. Yehoyakim ruled only 11 years in all!
Radak: This was the beginning of Nebuchadnetzar's eighth year. In Yirmeyah (52:28), it says "ha'Am Asher Heglah Nebuchadnetzar bi'Shnas Sheva"; it was the end of his seventh year and the beginning of his eighth. There are many Perushim like this in this Sefer.
Radak: According to Seder Olam, the seventh year from when Yehoyakim was conquered was Nebuchadnetzar's eighth year.
QUESTIONS ON RASHI
Rashi writes that Yehoyachin went to do Melech Bavel's will. If so, why did Melech Bavel depose him and take him to Bavel?
Radak: He thought that he will rebel, like his father did. From a bad dog does not come a good puppy! Therefore he deposed him and made his uncle (Tzidkiyah) king in place of him.