Hi,
Yes, it is normal procedure to have your pet stay there all day. However, I remember your post about the how they took your baby w/o you there.
i'd be looking for a different place to take him for his surgery. They still put him under, and if I had any concerns with a vet place at all, I would not ever let them do a procedure that involves putting my animal under.
For me I have to have trust in my vet and the place . It would be hard if they had already done something in the past that I questioned.
you may be better off looking around for a better vet hospital.