1)
Why does it say "Avarecha Es Hashem b'Chol Es"?
1.
Radak: Since He always does miracles for me. I am obliged to always bless and praise Him.
2.
Radak (from Shocher Tov): "Es ha'Kol Asah Yafeh v'Ito" (Koheles 3:11) - even insanity. (Because David acted like a lunatic, Avimelech expelled him and did not kill him.)
3.
Malbim: Both at good times and bad times, for I believe that the bad is for a good purpose.
