This post is to help anyone else who might run into the problem I was having when I created my first civ.
I followed the instructions, and when it said "you can now play your civ", I tried, and it didn't work. So I fried my brain searching for errors. I found the following errors:
typos (custom_civ was custmo_civ or something)
wrong reference (txt_key_leader_custom_pedia was txt_key_leader_custom or something like that)
picture dimensions (513x512 instead of 512x512)
dumb stuff I did when I didn't understand why I was doing it (unitclass_custom_archer instead of unitclass_archer)
After fixing all that, it still didn't work. I could load the mod, but when I got to the civ select screen, it would crash when I chose my custom civ. I spent hours searching this site and my files and elsewhere on the internet. The solution was this:
I copied the files and folders from assets/art to assets/xml/art and everything worked fine. The tutorial directly references the first, and the downloaded "newciv" creates it, but putting those files in the second location was my solution.
If this helps anyone else, I'll be super happy, cause I was about to swear a little swear wordy.
PS Thanks a ton for the tutorial - turned months into days.
PPS Whoever it was that posted that this is in fact the HARDEST civ to edit was right. It is not the easiest to edit, it is just the most editable - the difference matters to a noob.