seroMack“"I live in a small house with my parents and my brother and sister"”
The sentence is correct but you could shorten it: I live in a small house with my parents, brother and sister.
seroMack“I have a father.”
Correct again, but rather odd. I don't know anybody that doesn't have a father, either dead or alive.
seroMack“My father is a sculptor. I always talk to my/the father when I want to ask him something."”
Don't use the when you talk about your own father or mother. You could say: I talk to him when I want... (I don't understand how you could ask your father a question if you didn't talk to him, though. Perhaps you could e-mail him...
seroMack“"My favorite instrument is a the cello and I can play on it"”
)
I can play the piano.
He can't play the guitar. (But: He can play chess.)
He played that song on the piano.
CB