You answered your question.. some details here: yes, you do need driver packs and they must be distributed. The 'special' thing is that the machine will only honor drivers that are on ANY DP in its boundaries (so you can distribute packs to limited set of DPs.. I strongly advise against that though).
The process is generally: - The machine creates a list of PnP IDs frmo out of WinPE - The list is sent to the MP - The MP queries what drivers that are in the selected categories, are enabled and are available on the DP in the machines boundaries are available / applicable - The list of drivers is sent to the workstation, downloaded and installed.
NOTE: Some devices 'only' appear with correct IDs after a 'base' driver was installed (happens on a couple of USB dongles that 'switch' between disk and other modes); for those, Auto-Apply generally does not work as expected (WinPE only reports the initial IDs, not the morphed ones).