When the dog is relaxed it will curve at the tip but be mostly laying flat downwards but yes, when the dog is alert the tail does go almost over the back in some cases.
no they dont some dogs have little stubs as tails
No, they have straight tails.
curly tails
no. they curl their tails when they are happy.
They had it when they where born
Shih tzus can have curly tails, Shiba Inus...
Pug Boston terriors have curly tails because they must have got that part from the pug parent.
No.
Yes
no
No. I have a pet boxer who had puppies, and they are actually born with really long tails. Humans cut their tails off, and I don't know why.
Labidoor Retrevers have curly tails. and so do keshoonds