You need to modify several files outside of the civ3mod.bic
For units, you need to create a folder with YOUR unit name in the Art\units section (i.e. "Militia" or whatever)
Then you need to copy the contents of the folder from the unit ICON you used (i.e. Warrior) into the new folder, then rename ONLY the warrior.ini to militia.ini
As for new civilizations, you need to look at the Text folder, specifically to Pediaicons.txt file.
You should be able to figure out from there what chages you need to make to FULLY add your new civ to the game, eliminating crashes at some of the advisor screens, etc.