It's a myth. Dogs (especially males) will urinate on fire hydrants, poles, doorways (anywhere another male has urinated) because dogs need to mark their territory and one dog letting another know where they have been.
Yes, all dogs urinate.
Urinate.
Yes. All animals and humans can urinate.
Yes.
they don't urinate on their food or drinking water
Yes
Dogs urinate, defecate and respire, these are all forms of excretion.
no
Their bladder tells them "it's time"
Their scent.
Yes you can, such as a cat has a litterbox. Only you'll have to train it to urinate in that place.
from their urethras the same as male dogs and ALL other mamals who urinate!