Remnants on movement and picture off-screening

Call it a png file – MSPaint can save different kinds of files, and different versions of paint have different default file formats, so that is ambiguous, like “house pet” (so dog? cat?).

Clearing with background and redrawing is usually the best way.

Yes. Use translate(). See recent discussions:

One important thing – don’t draw your character and background onto one image! Draw your character on one image, draw your background on another, import them both.