they're GIRLS!!!
get used to the 'interior decorating', girls are complete messy horrors
they're just making it how they like it, shredding newspaper is a fun ratty activity and also used for extra bedding.
Up-ending the bowls is either they've hidden the food somewhere else, or they're trying to use the bowl to hide the food. Rats stash food so other rodents or rats don't find it and eat it.
the fact they've just started doing it, if they're relatively new to you, means they're fully settled and have taken charge of their cage as 'theirs'.
keep putting stuff where you want it as it gives them something to move about and arrange it to their needs.