The best time is now. The second best time is tomorrow. The third best time is please RSVP by September 1st.
Your kids are absolutely welcome. Someone else's kids are not welcome. Please leave any children that are not yours where you found them.
Yes, there will be parking.
Yes! Please read about it on the travel page.
A taxi might be the simplest solution (~$100 from Dulles). We'd love to see people carpooling using page we setup for that: http://www.groupcarpool.com/t/4rgmi3 We also strongly suggest contacting friends you know are coming and trying to coordinate car travel. Walking is another option... a very bad option.
The venue is non-smoking, but a short walk off the property is an area where you will be allowed to smoke.
We can't blame you for wanting to stay in DC - it's where we met and has a special place in our hearts. If you go this route you might have a hard time making the first (entirely optional) event on Saturday night but we'll understand. You'll have to either rent a car or take a taxi out Sunday morning. Beware of DMV area traffic!