First of all, you need to read Hydroguy's excellent tip thread, specifically the guides for WDW vets:
http://www.disboards.com/showthread.php?t=1520483
I'd recommend 3 day park hoppers at minimum. That way, you are getting at least one Magic Morning, which comes with 3- or more day hoppers.
Even better is 4 or 5. Then you can go at a leisurely pace, take midday breaks, and do all your favorites more than once.
As far as days per park, because the two parks are literally one minute's walk across the Esplanade from each other, most people hop from park to park as DL gets crowded. See also on that Tips thread: "Why I Parkhop at DLR"
We have stayed for 5 days-- arrival day afternoon/evening, 3 full days, and departure day morning and early afternoon. It always seems perfect for us!
Also-- Halloween time is very busy at the parks, especially the weekends! Because of the Mickey Trick or Treat parties in CA on the weekends, and just because of the extra decorating, theming, etc. the parks are pretty much nuts. You might want to avoid Halloween weekend unless you really want to do the ToT party. Maybe you could do your other parks and sightseeing over Halloween weekend?
Have a great time planning! Hope you enjoy Walt's park!
