The POP Demand Mod Forum is where all discussions and interactions about the mod happen. POP Demand Mod (PDM) was started on the Paradox Interactive Forums, eventually gaining its own Sub-Forum inside the Victoria 2 forums, becoming probably the most active VIC2 mod.
Anyone who owns Victoria 2 can download PDM and post on the PDM forum, on just about any topic related to the mod (i.e. feedback, suggestions, gameplay, technical issues, etc). The mod is quite open to new ideas and anyone can suggest them, you don't need to be a "member of the mod team", because PDM has no formal setup, as such.
Naselus is the founder and lead developer/designer of the mod and is the man who ultimately decides what goes into the project. Rylock is the sort of "second in command" and takes over whenever Naselus is unavailable. PDM has many other regular (and irregular) contributors who make parts of the mod, do play-testing and bug reporting, and give feedback.
If you think you have a good idea that could improve the mod, then suggest it in the POP Demand Mod Forum.