Is there any way to export modified photo (info added) without making it take more space? Somehow "Jpeg quality" setting messes up file size even if I don't edit images in any way.
If you notice, that the exported JPEGS file is much larger when exported with JPEG quality "Maximum", use "JPEG Quality Large". "Maximum" is only useful, if the original JPEG used this compression setting, but most JPEGs taken with my digital cameras are having a file size hat corresponds better to "Large". You should also use "Maximum", if you want to add more edits in an external editor. Each compression step will be reducing the quality. As long as you want to edit the photo, keep the quality at maximum, and save the final version with "Large".
Also, what "most compatible" color profile will do differently compared to "original"?
Whenever I am using this setting for my photos, the original color profile will be replaced by an sRGB IEC61966-2.1 profile. It might be different for scanned photos, but I have not tested it.