Why did he say "come to me"?
Radak: He could not go quickly due to the weight of his Kelim. He saw that David has no armor - David can approach quickly!
Radak citing Vayikra Rabah 21:2: The ground held him and he could not move, therefore he asked David to approach. 1
Malbim: It is disgraceful of me to go to fight with [someone holding only] a stick and stones.
Did he not see that Hashem is doing a miracle for David?! Etz Yosef (on the Midrash) - his limbs became heavy, as if the ground held him. Maharzu on the Midrash - it truly held him. (Perhaps he saw the Hashgachah, but it was too hard for him to retract. Even Chananyah ben Azor, who was initially a Navi Emes, when he saw that he would die within the year, like Yirmeyah said, he commanded his sons to delay his burial, lest people see that he lied and Yirmeyah was right (Radak Yirmeyah 28:17, from Midrash Tana'im Devarim 13:3)! - PF)
Why did he say that birds and animals will eat David's flesh?
Malbim: I wanted to settle the dispute between our nations via a fight between two representatives (refer to 17:9:1:1 and the note there); then the defeated man is buried. Now you come to fight me with a stick and stones to disgrace me - I will leave your flesh for birds and animals!
Why did he say "ul'Vehemas ha'Aretz"? David said "ul'Chayas ha'Aretz" (verse 46)!
Rashi (from Midrash Shmuel): Behemos do not normally eat people. David said, he lost his mind - I will surely defeat him. David said correctly (Chayos eat people).
Radak: They are the same; Chayah is included in Behemah - "v'Zos ha'Behemah Asher Tochelu
