- Are there any very basic tutorials about the Galaxy Editor?
Yes, you can learn to use the Galaxy Editor here.
- StarCraft II mapping is so confusing! Is there any starter guide so I can quickly work out more things?
Sure! Try the Starter Guide.
- I can't seem to find the Campaign Units, why?
You must add a Campaign Dependency at the top of the list of your map's Dependencies (found under File -> Map Dependencies).
- Why can't I see the Omni-Lights I am placing?
You need at least the 'High' setting for the "Lighting" Graphical Setting.
- How do I place and assign Start Locations?
To place one, go under the "Point" layer and select the 'Start location' option. To assign one, go under Map -> Player Properties.
- Somehow, it looks like the last dimension (array) of my variable never triggers, why?
The 1st array is "0", 2nd is "1", and etc. You probably have started with "1" instead of "0".
- My upgrades aren't working properly. Any ideas why?
Don't set the max level for your upgrades to a number higher than 127; doing so will cause the upgrade not to function more than once.
- How are the Players' ID assigned in the lobby?
See Player ID.
- How can I properly duplicate an unit?
After right-clicking the unit and pressing "Duplicate", select -ONLY- the unit's actor.
- What is the doodads limit?
- How can I quickly test my map without having to publish it every time?
Ctrl+F9. And do not close the StarCraft II window once you're done with the test: if you alt-tab back to the editor, the map will load much faster the next time you test it.
- How do I open maps from others?
When downloading a map directly from Battle.net 2.0, it gets stored into a cached temporary file and is thus inaccessible. The only way to open maps is to open them from the Editor: Ctrl + O. From there, you're on the tab "Local Files", change to "Battle.net" and Voilà! Only Unlocked maps are listed there, unfortunately.