A small plugin that will display a random image from your native WordPress photo galley or in-beaded images.
A: Sure, just add a second or third widget to the sidebar, but you can't do it from within this widget.
A: No, you may only display a single category per widget
A: Make sure the category you have selected has pictures in it, if it doesn't, nothing will be displayed.
A: Unfortunately, no. WP Super Cache caches all php built html pages for quicker page loads. Since the Random Image Block is built directly into the html page, with WP Super Cache enabled, you will see the same random image on the same page until the cache refreshes. Each page will still have a diffrent image, but they will not update for each page refresh. Currently there is no work around.