Newbie Kegging/regulator questions

I just got my kegging equipment from kegconnection and after looking at it all and reading several threads. I have a few questions:

1. If I am natural carbing, does it hurt anything to just put the priming sugar in the keg and close the lid, without putting any CO2 in?

2. I have a dual body regulator with check valves, does it matter when I open these, and do I always leave them open?

If you naturally carbonate, you need to still seal your keg with a few seconds of CO2. Just start pumping it in and release air with your pressue relief valve every few seconds. This will seal the top.

How do you know when to stop putting CO2 in?

I don't naturally carb in a keg but I can sure hear when my lid locks in place. Usually I am pumping in 30psi, can't tell you a time because it depends on the keg/lid. Put some keg lube on the rubber o-ring and if you have a tight fitting lid you are going to get a good seal quickly. Check it with some StarSan spray for leaks.

After your beer is carbed and your not serving you can shut down the gas valves to be safe in case something at the keg end is leaking CO2. Some people leave it on all the time, I have lost a few tanks of CO2 so I play it safe.