Yes, all frames will be in memory prior to making the GIF. Probably fine for most GIFs, but if you want to go FFmpeg | ImageMagick | FFmpeg for processing a video, or maybe for a longer GIF, you can use this script to keep only a frame at a time in memory: http://www.imagemagick.org/Usage/scripts/process_ppm_pipelin...

Not sure, actually. Never had it be enough of a resource hog to even think about it.