I'm not sure how long you've had Lucy, but when I first got my ball python, he would stretch up as though trying to escape. I later shrugged this off as him exploring his new surroundings because this behavior stopped within a week. Although I've seen elsewhere that if this behavior continues, your snake may be stressed. As for the sitting on the hot spot, to me it just sounds like (if you have a heat lamp or ceramic heater,) your lamp needs to be moved closer. Be careful about that though (I'm sure you will be, it sounds like you really care about your snake!! <3)
ps: this is like, my second day on this site and this is my first post, I'm still pretty new to snake keeping so you may want to get a more experienced person's advice from here before taking mine to heart heh,,
-best of wishes my dude