[Christ]

Re: Battery life - once you've warmed the engine, the battery is in a warm environment, and outside temperatures don't affect it so much, unless it's not in the engine compartment.

EOC at night while running everything known to man - Keep in mind, your alternator has to recharge your battery using power from the engine... by doing this at night, using all that crap is costing you a large chunk of your instant mileage, because each time you start the engine, it has to work harder to recharge the battery from the intermittent drain.

Keeping it charged - You really should have no problem with this, actually. Most batteries have a reserve capacity of nearly 1/2 hour, and some up to 90 minutes. They can outlast anything you're going to throw at them for 3-5 minutes of coasting, and cycling a battery a little deeper than normal won't hurt it either, to a noticeable extent, as long as you're not going too low.