I think it depends on your eating style. I don’t think we have ever stayed more than an hour even with characters. But we are fast eaters.
In theory, if you were to get in on time, eat for an hour or so and still allow 90 minutes for travel (here too- we have never had that long of a wait to get from park to park) I think worst case, you get there right on time. Looks like you are familiar with the parks so you should be able to navigate quickly! Otherwise, take a cab?
As far as Garden Grill ( I think that is where you mean?) We thought it was fantastic twice and not so great once. You can find the menu on allears.net under dining. I don’t remember there being options, just the platters.
The characters have always been Mickey, Pluto, Chip and Dale for us. Not sure if they always change or what the schedule is.
It is a fun place as far as the environment though!