Great it worked out for you. Smooth polys require more computer resources to render, so avoiding them on complex entities is preferable, but of course, depending on the map, one may want the slightly nicer look.

To change it to straight, right click :CC2EXPLODE: and pick the Smooth to Straight command to use on your poly. The process is also reversible with the straight to smooth option.

(Keep in mind that it will be easier to notice the difference inside CC3+ than on the exported image)

[When you convert the coastline to straight, you may notice a weird spike near the top left. This is caused by you going back and forth when placing the nodes, causing the lines to pass over each other and create a really sharp angle. I noticed it earlier, but the smooth polygon kind of hides it much more effectively than a straight one, so you may wish to go in and remove the offending node with :CC2DELNODE:. The node is located in the middle of the "cross" where the line spikes, not at the edge of the spike.]

It means you have selected the entity to trace at the wrong point. The trace will always go through the point on the entity where you selected it.

(Note that it might go the wrong way around untill you have moved the mouse enough from your starting point to pass the selection point)

Ah, I see. It is just the name of a tool from that style. I don't really know the purpose of it, but it is just drawing a regular polygon. Mayby it is intended for drawing polygons that you can later use a cut operation against, but there isn't anything cutting or cutted in the tool itself.

The resolution during export is the same as on screen, it picks the appropriate resolution based on the actual size of the symbol in the image. You can force it by selecting Very High before exporting, but it shouldn't normally be needed, as you won't get a benefit from using the very high symbol as a base if it is only going to occupy 10px in the final output anyway....