What is the definition of "S'lav"?
Rashi: It is a fat bird called 'a quail'.
Why is "S'lav" written with a 'Siyn' and not with a 'Shiyn'?
Yoma, 75b: Because on the one hand, for the Resha'im, it felt like a pipe (Silon) in their throats, the Tzadikim ate it in tranquility (be'Shalvah). 1
See Torah Temimah, citing the Mechilta - which has a different version of the answer.
How will we reconcile this Pasuk, which writes that a layer of due fell on top of the Manna, with the Pasuk in The desert (11:9), which describes how the Manna fell on to a layer of dew?
Rashi: In fact, the Manna lay between two layers of dew, as if it was in a box, thereby keeping it fresh.