On sit-down restaurants you get a 20% discount, but an automatic 18% gratuity is added to your bill. There is no discount on quick service food.
You can get up to a 60% discount on Disney resorts if you are actually staying in the room, and up to 40 or 50% if you aren't. The discount depends on how far out you make reservations but mostly how busy it is. If you call to make reservations around a busy time you might be able to split your stay to make your total cheaper, but there's no good way to do that through the website.
The information about local businesses is in a booklet that you can get on property, they put out a new one at least once a year and I don't remember what kind of stuff was in it. I do remember getting a bit of a discount at Sweet Tomatoes and Golden Corral, and I forget if Cici's did a discount or if we had some sort of coupon that time.
Your maingate pass is only good for 6 days, up to 3 people, so if you only take one other person, that still takes up one whole day. The maingate has blackout days, they're different for each park but the list will be available on the hub.
COMPLETELY SEPARATE of the maingate, there is a cast discount on all tickets. You have to purchase them at a Company-D, neither guest relations or vacation planning can discount.
Some other stuff they don't tell you about are the cast previews (which I'm sure they'll do for the fantasyland expansion) and different cast events and tours. There is often extra stuff for CPs within different areas like wishes cruises, we got to do a backstage thing at Kilimanjaro Safari where we boarded a truck backstage THEN drove TO the attraction and they pointed out all the evac exits and hidden fences and stuff.
