Automatic Thumbnail generation and different cache folders

Hello,
beside the very good image gallery I noticed, that if some images are updated oder modifed the thumbnails have to be newly generated. The only possibility is to clear the complete cache. What then results in long loading times until the thumbnails are generated again. So me feature requests are:
1. subfolders in the cache in order to clear the cache per gallery
2. possibility to generate all thumbnails for a gallery in the admin pages
thx
chris