[bsmith0404]

If you have space to adjust the catch plate without it causing problems while stationary, I'd start by doing that. I've found that cardboard from a cereal box makes a very effective spacer and can easily make small adjustments by adding more layers. If that doesn't work for you, a simple towel on the floor across the bottom of the door may do the trick.

As for protecting the walls from the door knob, get the round rubber bumpers that stick to the wall with two sided tape. About a $3 purchase at Walmart or any home improvement store.