Three days (ημερα τρεις). A parenthetic nominative (Robertson, Grammar, p. 460).

What to eat (τ φαγωσιν). Indirect question with the deliberative subjunctive retained. In the feeding of the five thousand Jesus took compassion on the people and healed their sick (Matthew 14:14). Here the hunger of the multitude moves him to compassion (σπλαγχνιζομα, in both instances). So he is unwilling (ου θελω) to send them away hungry.

Faint (εκλυθωσιν). Unloosed, (εκλυω) exhausted.