Question 1 - may be a situation where you have to see it... but the fact that the batter stepped back toward 3b dugout - makes me lean toward interference. There is no provision for intent.
Question 2 - If the ball goes out of play from a pitch. 1 base. The rule is from the rubber - not the mound. If a P goes to pick off a runner at 1b as he hop steps and throws, he has not disengeged the rubber and if the ball sails into the stands 1 base. Same play but P steps back off the rubber and ball sails into the stands 2 bases. Since he disengaged the rubber he is now a fielder - no different than a SS or 2B.
Rule of thumb - 2 bases awarded from any fielder when ball thrown out of bounds. The award is determined at the last base legally obtained by the runner at the time of the throw, not the time it went out of play. A pitcher on the rubber is not considered a fielder (for this rule).