“mixed multitude.” When Israel left Egypt, referred to as “the Exodus,” so many Egyptians and people of other nationalities had been impressed by Israel and Israel’s God, Yahweh, that they left Egypt too and went with the Israelites (Exod. 12:37-38). These non-Israelite people were referred to as the “mixed multitude.”
“a lust, yes, a lust.” This is the figure of speech polyptoton, where a word is repeated for emphasis. It means a great lust. [For more on polyptoton and this way of translating it, see commentary on Genesis 2:16].
“wept again.” The Israelites had murmured and wept several times since leaving Egypt.