1)
What is the meaning of "v'Lo Nichbad Alecha"?
1.
Radak: We should not all be with you, for it will be expensive for you. Malbim - if David will go, also all his servants must go with him!
2)
Why does it say "v'Lo Avah Laleches" after giving the reason he refused?
1.
Malbim: Initially David declined lest it be expensive for Avshalom. When Avshalom persisted, David answered that he himself does not want to go.
