I have a few questions about the trip from Las Vegas to the Grand Canyon...?

I've only been to the West Rim from Las Vegas. However, you shouldn't run into much traffic after getting out of Las Vegas. The only traffic we found was approaching the Hoover Dam. They hadn't opened the new bridge yet and had to inspect every vehicle that crossed the dam. Since the new bridge is open now, I wouldn't think that traffice would be a problem anymore.