Yes. A single image is converted to a static GIF. To create an animated GIF, you would need multiple frames.
GIF supports binary transparency (a pixel is either fully transparent or fully opaque). Semi-transparent pixels from PNG will be converted to fully transparent or opaque.
GIF uses a limited 256-colour palette. Images with many colours may actually be larger as a GIF than as a PNG.
Yes. Upload multiple images and they will be combined into an animated GIF with each image as a frame.
Set the frame delay (in milliseconds) before converting. 100ms per frame gives 10 fps, which is a common GIF frame rate.
GIF supports a maximum of 256 colours per frame. Images with more colours will have their palette reduced, which may cause visible colour banding.
Yes. The output GIF loops infinitely by default, which is the standard behaviour for web GIFs.