Zevachim 15b - Two quick hearos

1. The mishna gives a list of people who are passul for doing kabbalas ha'dam, the second being an o'nen. Rashi defines an o'nen - כל זמן שלא נקבר המת, pre-burial. This doesn't seem accurate because the din o'nen in the Torah who cannot eat ma'aser sheini or kodshim is even after the burial, so long as it is the day of death. The Rambam in pirush hamishnayos writes explicitly that the o'nen we are referring to here also is one who lost a relative that day, regardless of whether it is before or after the burial. Rabbeinu Yona in Brachos elaborates about this that chazal extended and modified the definition of o'nen and applied it to any preburial situation even after the first day, but this isn't the definition when used by the Torah. Does rashi mean to say that pre burial even after the day of death an o'nen would passul the korban by doing kabbalas ha'dam on a rabbinic level?

2. The Rambam in the pirush hamishna points out that kohanim would not wear tefillin shel yad when doing the avoda because it would be a chatzitza between the bigdei kehuna and his skin, but would wear the tefillin shel rosh would even be worn by the kohein gadol between the tzitz and the mitznefes.