Welcome to the Guild! We have quite a few users of CC3 - Gandwarf and NeonKnight being the primary ones, so you're not alone. There are a few CC3 and City Designer Tutorials in the Tutorials Forum - check those out.
While I don't use CC3, I created all the symbols for the upcoming SS3 Modern Symbol Set - I'm not sure when that will be released, though.
Again, welcome, Zephyrtt!