Can I use cadê?
why not "onde é?"
That should be accepted
Would it be wrong to use fica instead of está?
Ficar is used like "Estar", that is, something that cant move. If the question is about where the crib is at that moment, you cant use "ficar". But it can also be "ficar/ser" once we dont have a context
Cadê o berço do meu irmão is incorrect why?