re: If Luke has these great Jedi powers, then why is he dragging his near dead dad?

It was only being protected by the shield on Endor because it wasn't completed (I figured that was obvious by the fact that half of it was missing). The emperor tricked the rebels into thinking it wasn't operational, but it was. It could fire it's main weapon on the bigger ships, but it still wasn't complete. Once it was completed, it would've been like the original Death Star.