When does CoS come into play? How many values are there, and in what priority (low number is low priority or is higher number?)
Where can I find more information on CoS values? I've looked, and it seems like I can only find references to them in MPLS docs.
"So is IP precedence (0-7) the L3 equivalent to CoS"
Kind of. There are the same number of values and so you could map them across. And because DSCP is backwards compatible with IP Prec then you can map CoS to DSCP which is exactly what a switch does.
IP precedence is a subset of DSCP as DSCP used more bits in the ToS byte than IP precedence.