Camping at Trail Camp has two drawbacks: Higher means colder, and 2: people are affected more by the altitude there--staying overnight lower reduces that risk. Of course the benefit is that you are closer to the summit.
Outpost is 2k feet lower, so you are several hours of hiking from Trail Camp, so adds 4 hours to your time to summit and return to camp. Big advantage though is that you don't have to haul all your overnight gear that extra 2k' elevation.
As for the road, my wild guess is sometime in June.
