1)
What is the meaning of "v'Acharei Achitofel"?
1.
'Rashi', Radak, Malbim: After he died, David took Yehoyada and Evyasar in place of him.
2.
Brachos 3b: Chachamim came to David, and said that the nation cannot support themselves financially. David told them to go to war. After taking counsel from Achitofel, they consulted the Sanhedrin (Yehoyada), and asked the Urim v'Tumim (Evyasar).


