Contour maps in this case are vector files that contain contours at different altitudes (or climate or temperature or rainfall). These vector files can be exported with unfilled contours or fillled contours.

FT3 has a practical export image size around 6000 pixels in a single image. You can, however, zoom in on a few parts of the image and export those images at high resolution, followed by assembling those images in an image manipulation program such as the GIMP. The multi-image export feature in FT allows multiple zoom levels to be output and these can then be assembled into a larger image. The big question I have to ask, though, is "how large an image are you trying to get?"

If you'd like ice caps (a type of climate) to appear on a non-climate views, then you'll need to do something like exporting a climate view (with ice caps) and your desired non-climate view, then assembling the two images using an image manipulation program like the GIMP.

To get ice caps on the sea from the Image Climate shader, you need to specify an image for land and sea that have ice caps in the same relative place. If you don't case about sea showing as blue, setting the land and sea images to the same image will get you ice caps that are continuous across land and sea.