DSCF are only for DAZStudio; if you also intend to use DAZStudio, then the DAZ CF should be installed into the DAZ content folder.

Ps files are designated for Poser and should be installed into Poser runtime folders. Many others and I do not install Poser content into the Download folder, it can cause runtime bloat and subsequently slow down your app to a crawl. It is adviceable to create several separate runtimes simply to organize your content and to easily find items within your Poser Library.

Any PoserCF which also requires a base file should be installed into the same Poser runtime. There are files necessary for complete functionality and without the presence of these files within the same runtime folder(s) you will not be able to use the characters properly. BTW, the Aiko 4 Base files must be installed along with the Victoria 4 into the same folders; she is a morph of V4 and not a separate figure like the DAZ generation 3 figures.

DSON Importer is a script and must be installed into the main Poser folder. That is the folder that exists within Program Files. Now, if you intend to use Genesis/Genesis 2 then you must install the DSON Importer. This is the only way you can load them into Poser. ATM, I would advice you not to install DSON yet until you grasp the fundamentals of installing, loading and using figures within Poser. Genesis/Genesis 2 require a very different approach and I think that your skill set is not ready for this yet.

If you need more information about DAZ files listed in your DIM, click on the information icon located next to file name and a product webpage will open. This page will contain information and guidelines. This is illustrated below: