Yes, getting from line level (even consumer -10db line-level) to mic-level requires attenuation.
Going from "headphone out" into line-level can very often be done directly. Impedance is not an issue here, only signal levels. And often the signal levels are compatible enough that no extra interface trickery is necessary. Note, however, that generally speaking "headphone-out" is not as "clean" an output as the main line-level output from most audio equipment. It is certainly sufficient for monitoring, but not as the "main path" for your finished product.