Urgent! 4 year old King Charles Spaniel bad behavior

Urgent!!!
Oscar (male) my four year old King Charles Spaniel is a very moody dog, when we leave the house he tends to urinate somewhere inside the house even though he has a dog door that is always open and he knows how to use and uses regularly. On the rare occasion that the door to my room is left open he enters the room and urinates in my room, only when I am not in the room, or just recently he came into my room sniffed at the place he urinated earlier that day, walked out of the room and defecated at the top of the stairs right outside of my room door. Oscar is a rescue dog and we got him at around the age of 2 and a half, so we have had him for a while now, we live in the UAE and he was found tied to a lamppost in 50°C (122°F). We believe that he has separation problems an the fact that we are moving house is causing him to become anxious. The house that we currently live in has tiled floors, making it less damaging when he does create a mess, however we are moving to a house with mainly carpeted floors and really need help to iron out this problem.

Less Urgent!
Now, Roxie (female) my second dog who is a mixed breed, also a rescue, she is about 1-1.5 years old now, and she has had this problem for a long time as well as with the previous owners who were not ready to have a dog and abandoned her. When Oscar dedicates or when there is feces outside, Roxie tends to come and eat the feces, we have tired everything to stop her from doing this as it is extremely disgusting, we have tired putting some pineapple juice on their food to change the smell of it, we have heard of people putting hot sauce on the feces but have never tired because we don't want to have to possibility of her getting sick. We are really stuck and don't know what to do.

Any help is greatly appreciated.

Thank you