Chapter 3.3 - excercise on decoupled arbiter is confusing

[wunderabt]

The hints contained 3 points that confused me:

• "consider having an internal wire of the selected channel" but the solution has no such wire. Is there really a point in using a wire or can this hint be removed?
• "PriorityMux(List[Bool, Bits]), which takes in a list of valid signals and bits, returning the first element that is valid" where I figured bits would refer to the bits from the decoupled interface. But I guess any data works, right? Maybe a more general term like data can be used? [reading it again it's clear that the Chisel bits type is meant so I don't know why I got on the wrong the track here]
• the solution uses foreach which was not introduced in the chapter. Would a map work too?