P: Ability to arrange & customize save-as file formats so popular formats are at the top

Any chance you can make it so, Mr Cox? (Long time no chat! 🙂 )

You can only remove them if the format is a third party plugin format.
Otherwise: no.

I posted this on the Photoshop Facebook page and was asked to bring it up here, so...

"Is there a way to remove options from the "Save As..." menu in PS CC 2014? Been looking everywhere and can't find a way of modifying the list. Quite happy to do Registry changes.

Just don't need all the options that are there - such as Dicon, IFF, JPEG 2000, JPEG Stereo, Multipicture, Pixar, Portable Bitmap, Scitex, Targa... Never saved a file in any of those formats and doubt that I'm going to start now"

One I will NOT be removing is Large File Format...

I'd love to be able to edit the Formats list on the Save As dialogue, so that when I go to save a file, I don't have to wade through all the formats available when I typically only use a few.

I could see a tab or section in the Preferences dialogue that gives me a checkbox for each format, allowing me to quickly turn available formats on and off.

If keeping all available formats is important in the Save As dialogue (I can see an argument for that), then maybe giving the option to enable a separate list called "Preferred Formats:" with only your chosen formats. This way, it allows both drop-downs to be visible, and the user can choose which to pick from ("Formats:" or "Preferred Formats:").

»And maybe allow us to remove ... large file format that nobody uses.«
Are you joking or have you just never worked on images above 2GB in size? (Edit: Naturally you could just prefer to use tiff for files that size, but claiming no one uses psb seems peculiar.)

The issue has been raised in the user-to-user Forum occasionally, too, so it seems you are not alone with the wish for customization for that dialog.
But in the meantime you could look into a Scripting solution for your personally-most-popular formats.