You can pretty much expect the Food & Wine Festival to be much more crowded on the weekends than during the week. Plus, factor in the first day and it will probably be even more crowded. I was at F&W Festival the first day two years ago in the early afternoon and it started out somewhat crowded. We were only there a little over an hour and by the time we left, it was getting very crowded. Some lines for the food booths were 20 - 25 people deep.....much too crowded for my liking.
Oct. 18th will be the first day we're at WDW this coming trip but I'm not planning on going over to EPCOT until mid-week...then again, I have that option this time (which I didn't two years ago).
I would think that Future World will be a bit more crowded than normal but it should be manageable. World Showcase will be pretty packed and I would avoid it that first day....if you can. It's not worth avoiding if you can't get back to the F&W Festival...you must get to that.