Victoria has a lot of morphs with selfexplaining names like "mouth open", but what are this huge number of morphs like PBMDC32 are for?
Can I delate them or are they often used?

Mostly they are unused morph channels. It's best not to delete them as when
you do go to inject a morph, there would be no place for it to go and you wouldn't
be able to use that morph.
You can get a free utility from DAZ called dial cleaner which will hide all of these
so you don't have to wade though them.  It works on PZ3s and CR2s.
If you have compressed them into PZZs and CRZs you'll have to uncompress
them first.

Are these data morphing channels present in P6 and not shaded?
Does DAZ Dial Cleaner work with P6?

Yes, at least as long as you save in plain CR2 or PZ3files - I'm not sure if it copes with compressed (CRZ) files or external binary morph targets. All it does is change hidden 0 to hidden 1 for the unused morphs.

The PBMDC and PBMCC channels aren't used for the main morphs - those channels are already named - but for add ons, DC for DAZ morphs and CC for third party (community) morphs.