None to speak of, other than Textpattern itself.
SLIR (a PHP script to automatically crop and resize images) is included as part of all-grid, and should install automatically when first used. If not, try visiting /themes/all-grid/slir/install. SLIR is set and forget; it caches all the images, and automatically handles garbage collection of your old/redundant images.
Note: most hosts impose memory limits on php processes like SLIR. To prevent the server running out of memory when scaling or cropping an image, a good rule of thumb is to limit the maximum pixel size of any side of an image to 2500px i.e. landscape images should be 2500px wide and portrait images should be 2500px high.
When you’re dealing with many images, the TXP plugin com_article_image is recommended on the admin side.
While you can edit all css properties directly in the Presentation: Styles tab of TXP, for complete control of the css head on over to /themes/all-grid/sass/. Note: this will require you using a SASS preprocessor to convert the contents of the /sass directory to a useable css file in /themes/all-grid/styles/.