Thank you for your feedback. If I had to redesign the colony GUI I would probably make different design choices. However I currently don't plan on reworking the GUI, there is a lot of code behind updating the GUI that may have to be changed as well and for now my priority is bug-fixing. Maybe you can rebind Alt+C to something else (a mouse button for example) if that is more convenient for you. You can do this by going to Settings > Controls > Mods.
Regarding right-clicking instead; I wrote the code for the colony selector a long time ago and not going with right clicking might have been an oversight. The next patch will change this and will let you move or assign units by right-clicking.