Hi, about new map/editing - you are perfectly right - it's already in my todo list, so that if you select map embed tag, then hit the U icon, selected map should be loaded (as this is most probably what user would expect).
Regarding changelog - I would issue one on plugin's page, but general rule of thumb is versioning: 3.0.1 - first number is a major, you should definitely update, second one - any major fix/feature, you should update if you had any problems with umapper, and the minor numbers are mainly for maintenance (when I recompile language files, fix some typing errors etc), so most probably you do not need that update (again, if everything works as you expect it).
Would try to wrap that add new / edit map feature till the end of this week. Let me know any other findings!
Thanks for you help!