He's a baby, you'll have to wait for him to grow out of those little idiosyncrasies
The freezing disappears as they mature and some of my Pleo's were fussy eaters at first. You need to hold it under the chin for up to a minute before they stop doing whatever it is they are doing and pay attention to the food. This is why camarasauruses became extinct lol, they were a bit slow
The shaking could be either Pleo just testing out new motions, Pleo being scared of the dark or Pleo being cold. My guess would be the first one or second one, he'll probably just grow out of it.