I'm setting up to submit a miniatures game; I understand the policy with respect to table size, but is there a standard amount of set-up and tear down time built into the planning, or do I need to request it specially?

There is no standard, so if you specifically need setup and breakdown time, make sure to request it.

Generally, when placing events I try to give an hour gap between events not submitted by the same group or company, but there's no guarantee, so it's always a good idea to call out specific needs.

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Derek Guder
Event Manager
Gen Con LLC

If anything, set it up at a friends house, and have him time you.  Then add 10% to that, just to cover being interrupted at a con..  Then plan THAT amount of time added to what the game time you think you will have is.
IE if you are setting up a game of axis and allies for a 5 player game (one player per country) that you plan on running for 5 hours, and 'set up of the board' takes one to two people 45 minutes, round that up to 50 minutes and that should give you a 6 hr slot..