Great first map in the style :)

I wouldn't use the same symbol size for such a gigantic map. You would barely notice them on that scale. Perhaps create it at 1/4 of the eventual size? It's difficult to say what would look good, but why not try a couple and see how visible the symbols are. Remember that at world scale a single ridge symbol might indicate a small mountain range.

It's one of the volcano collection.

I don't think the hill poly works in that context very well. It was set up to be home to small smooth shapes about the size of the chameleon hills. The other options are down to personal taste. Feel free to experiment.

The disadvantage of having a separate sheet for the edge striping is that if you decide to modify the land shape you will also have to do exactly the same modification to the new EDGE STRIPE sheet polygons.

That is indeed a hollow in there.

Thanks :)

I always make varicolour symbols.

Don't forget this is just a first draft. There may be many different versions.