Yes; most Greek god/goddesses could and did shape-shift.
Seeing as Poseidon turned himself into a horse to mate with Demeter, the answer is yes.
Pretty much all of the gods had the ability to shapeshift.
shapeshift is a verb. 'At midnight he will shapeshift.'shapeshifter is a noun. 'A midnight the shifty shapeshifter shapeshifted into a spoon.'
No they can not. Although the Warlock class has many pats he/she can summon the imp can't shapeshift
You can't.
Try Google
What kind of music do poseidon like
Poseidon had 52 kids like most Gods on Mt.Olimpus
Bats, rats, wolves and also mist
Just change your armor
Poseidon ?
The goddess Athena