A couple of things...
One, regarding options for map pins, I believe a prior suggestion for making the linked Topic's icon appear as the map pin was in the works already... but I have no idea if that has been dropped or will appear someday... or whatever.
Second, in regard to topic Icons, I have a thread of specific suggestions (
HERE) that people are welcome to add specific suggestions to. There were a few "+1" posts, but even now I don't see any specific requests/suggestions added.