I've gone ahead and updated the tool with Drag-and-Drop loading functionality, and fixed the button panel so it is now on the left and the image display is on the right side. This should alleviate the issue of the buttons moving around when resizing the images. I also managed to catch an issue when using the Iso-Left Rotate on certain image sizes, and went ahead and fixed that as well. Please let me know if you run into anything else or have any other suggestions!
I'll have to spend some more time working out how I want to add a file-naming system, but for now, the other fixes have been applied and the new version is up!