I've got a few facts and opinions on gumbos for the uninitiated.
If you would like to make a gumbo but you are afraid of roux-making, you have options. While diehard white guys will tell you that you have to make a roux by hand with flour and oil / drippings, you can buy either the jarred version or the powdered version of the stuff and make a perfectly fine gumbo, and anyone who tells you that they can tell the difference is a liar. You will save a half hour to an hour to boot.
The gumbo you get in a New Orleans restaurant is a "show gumbo." You can certainly make gumbos that thick at home, but these tend to be heavier on the roux or okra than what you'd normally find in someone's home. These tend to be smaller than average portions with a much heavier emphasis on the meat and veggies and more rice than normal.
Cajuns tend to not mix meats when making their gumbo (well, except for duck and oyster), while creoles tend to have less rules. Again, it's purely a preference and expectations thing. Do what you like.
File' is both a thickening agent and a flavoring agent. It is perfectly fine to eat a gumbo with roux and toss some file' in for flavor.
The easiest way to differentiate between a creole and cajun gumbo (and most foods for that matter) is the inclusion of tomatoes. Cajuns didn't have access to them early on and they do not feature much in the cuisine. I prefer the cajun style of gumbo and I've detested every creole jambalaya I've ever eaten. The tomatoes add nothing to the dish but sour flavors and wetter rice.
Anyone who tells you to put thyme in a gumbo is trying to be fancy. Gumbo ain't fancy.
The proper rice to serve with a gumbo is long-grained rice from Louisiana. You can use Jasmine in a pinch, but for the best experience, you'll want to avoid basmati, short grained rices, par-boiled, etc, etc.
Many people will make a mustard based southern potato salad and layer their bowl like this: potato salad on top of rice on top of gumbo. You're not looking to soak the potato salad in the gumbo, you're just allowing the gumbo to touch it and absorb some flavor.