"You are a girl."
Translation:Tu es puella.
Could the subject Tu be dropped in Latin? (As long as one conjugates properly? ) Just like we can do in Spanish?
Not only can you omit subject pronouns, you should in most cases. The only reason not to would be to emphasize it.
The verb can go most anywhere in most cases, though many prominent authors put it at the end of their prose writing in the classical period.