I can’t answer the question about getting back in during the Star Wars phenomena, but that probably is a risky choice in October.
The timing by boat to Epcot will take about 30 mins, walking can improve that timing, but generally if you plan for 30 minutes, you can for sure hit that mark. Obviously France is very close to the IG, so that’s not a problem. Depending on your restaurant, you probably only need about an hour, as they aren’t usually that busy at 2:40pm, so wait staff should be pretty attentive. I’ve personally eaten at Chefs de France in March at about the same time of day, and it was a generally relaxed meal, and service was not slow.
The oat trip back to DHS is about the same time, just in reverse order. Perhaps add a half hour for delays and the ability to see a few things in France while you wait. So, that means about 2 1/2 hours is what I would expect.