Very normal! Toddler are exploring their world, and that includes different ways of seeing the world (upside down) As for the shaking, it can be normal or a sign of an ear ache/infection. If she is showing any other signs of an ear infection, take her to the doctor :)
Yes and it’s healthy! Especially for sleep🥰
Completely normal it helps strengthen their vestibular system and to them it feels funny because of the different sensations