300 is pretty much the standard, 150 being a minimum, not an optimum.
Yes, all those programs are Raster programs, or Bitmap programs, or whatever is the correct terminology these days. They create images composed of a grid of pixels. As opposed to vectors, which are mathematical representations of shapes, and thus can be scaled and modified without loss of detail. That latter aspect isn't all that important if you are creating the art as large as needed in the first place, but is often a problem for those dealing with customers who provide a small, poor quality raster image and expect it to be printed much, much larger.
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