Carefully look at Fred's weekly reports on Ontbirds, also search the Ontbird archives over the last few years for the same period - that's what I usually do before any trip.
The Owen point trail is pretty well the best for late fall with the shorebirds, but keep in mind that hunting is allowed on Sat, Mon, Wed and Fri I think, the Owen Pt is closed on those days. You'll likely want waterproof boots, as I remember the trails were quite waterlogged.
If you have hip or even chest waders, you could try to walk out to Gull Island on non-hunting days. It can be quite interesting out there (owls are showing up now), we went out there a few weeks ago, but it was a lot warmer and we could just wear our shorts. It's a lot colder now.
As for restaurants, my wife and I like "Dougall's on the Bay" just about 1 or 2 km east of the park on Harbour St. In town, there's a diner called Rosie's at the corner of Main & Prince Edward, it's cheap and simple but the food is good, and the locals go there also.
Other than Presquile, consider also Prince Edward County (the bird observatory is at the tip), Brighton Wetlands (just south of the townsite) and Cobourg and Port Hope can be good for waterfowl. The towns are cute too.
