Starging PRU with remoteproc in kernel module

I have been researching how to use remoteproc to start a PRU, but I have run into a few questions that I can’t find the answer for.

To boot a processor you need to call rproc_boot() and pass an rproc structure. To get the rproc you’re supposed to use either the rproc_get_by_phandle() or rproc_get_by_child() functions. Unfortunately I don’t understand how to find out the phandle (or device) of PRU0 for example. How do I get a hold of an rproc structure for PRU0?

Secondly I would like to know if my understanding regarding the firmware assignment is correct. Rproc has a char pointer firmware property. Can you simply put the name (or path) of a file in /lib/firmware?