1) Yes, the door would have a safety feature. My son and I talked about this.

2) The creature was added for fun. First off, the creatures almost kill the main character and then they are riding them. I can see the Blurrg helping conserve energy over the long journey, but man that would be uncomfortable.

3) That droid was pretty awesome. It was briefly in The Empire Strikes Back. Sounds like there is more than one of them.

4) Not Yoda (this happens AFTER the empire). Probably just doesn't want to kill a baby anything. Plus, he was given the option to bring it back alive.

5) It either a puppet or CGI, so in reality it isn't alive.

Another question: How difficult is it to see out of that mask? Does he just 'sense' people coming from the side?