is it possible to have thumbnails not indented but justified with hero image (no left/right margin of outer thumbs)? Same question for folders.
See Tiger > Design > Page design > Max. page width. You can set that to No limit. If you do that, you'll probably want to alter the number of columns - see Tiger > Sections > Folders and Tiger > Sections > Images.
And is it possible to have them centered - e.g. if there are only two folders - and not left-adjusted?
Last-row centering is not an option with this skin.