Column in users list & image size

Hi, I just installed this plugin and it’s working great for my regular/custom posts. I’d love it if it would work for the users list too, though, as I have some custom fields there (including a custom image field I use as avatars) that’d be great to view in the user list, but it doesn’t seem to be an option at the moment.

I also had a question: For one of my custom post types I have an image column. However, I seem to be unable to change the size of the image in the column. Right now, it uses a small thumbnail file of around 60×100 and displays it at nearly 400×600 pixels, which is both impractical and unappealing. Am I overlooking an option somewhere?

Thank you very much!