I'm rather confused about the image requirements.

Am I to create my images at 2200x2800 (live=viewable) then "pad" them with 300 extra pixels on each side to bring the total dimensions to 2800x3400? The buyer sees only the 2200x2800 pixels, correct?

If so, the sizes given don't scale to each other. For example, a 22"x28" (live) print area doesn't scale down to 16"x20", it scales down to 15.7"x20", cutting off the edges of the image. Images in which the edges are important will suffer. In particular, some images are graphically "framed," the edges of which will become cut off. Correcting for this at smaller sizes will create a visible border on the larger sizes. What to do?

Also, a 2800x3400 image scales down to the 659x800 and 165x200 preview sizes, but then the preview will have a border (the 3" bleed area) which the buyer won't see in the final product. If I scale the 2200x2800 pixel "live area" picture down to the preview sizes the dimensions become 629x800 and 157x200 respectively, not what you require.

Any help would be greatly appreciated! I'm looking forward to joining the marketplace.