PATA (Parallel ATA) isnt really a new term but has been a more common short form since SATA (Serial ATA) has been around.
The MDD PowerMac G4 models have 3 PATA controller flavours on board. Those are an Ultra ATA 100MHz (as used in the Mac mini) one, another Ultra ATA 66MHz one and last but not least a 33MHz EIDE one.
The earlier PMac G4 models (including the preceding Quicksilver model) do not have the Ultra ATA 100MHz controller but only the two other ones.
All onboard PATA controller flavours will be supported by the initial MorphOS (2.6) PowerMac G4 release.

We are planning to have networking supported for all G4 models from PowerMac 3,1 (SawTooth) to PowerMac 3,6 (MDD)

Onboard Audio is only supported for the PowerMac 3,4 to PowerMac 3,6 range in the initial release and it will only be an output driver for now.

Onboard USB (1.1) will be supported for all models. Afaik only the MDD/FW800 model allows "upgrading" to 2.0 but this is not really supported for MorphOS yet. You can always add a EHCI USB 2.0 pci card if you need it ...

MorphOS supports a maximum amount of 1.5GB memory, even though you could plug 2GB
into the MDD models which have 4 memory slots. They are shared on all available CPUs.

MorphOS will (obviously) only support a single CPU for now. There are some ideas how to use the second, unused one as some sort of co-processor but this is nothing relevant for an initial (and even followup) release(s). MorphOS will stay a single cpu core OS for now and I don't see that changing for various reasons that have been discussed (to death) in the past already....

There are currently issues with some add-on boards like SbLive! audio and SATA SiI3x12 cards which have driver support inside MorphOS but don't work stable in the PowerMac G4. I am looking forward to have that fixed for the release...

bye
Frank