Thank you, great way to put it I get it now.I think the best way to put it is that PG and VG are carriers/dilutants for Nic and flavors. Nic can come diluted in either PG/VG or both as can flavors but almost all flavors will be diluted in PG. The flavors will need to be diluted further for vaping.
I have no idea about the ph but some mixes are said to need a drop of lemon or other adjustments for ph. That's over my head at the moment and I haven't seen much talk about it.