As for the pace of the show, I think some people are expecting it to flow like a movie. Remember, it's a tv show that I'm sure AMC wants to last for many seasons. The pace is just fine for me, but I'm partial to character development and not concerned with nonstop action.
The walkers in the barn all looked to be dressed kind of the same as the people. My guess is, they didn't want to kill their family members and are hoping for a cure (remember when Doc compared it to other plagues and viruses we've overcome?) That's why Maggie was so distressed when Water Walker died. It was family or friend that got lose.