Is this considered a swear word in ASL?
Yes, just like in spoken English, this sign is considered profanity. It should be used with caution and only in contexts where such language is appropriate.
Can this sign be used to mean a female dog?
No, this sign is specifically used for the derogatory slang term. If you are referring to a female dog in a literal sense, you would typically sign 'female' followed by 'dog', or simply fingerspell the word.
How important is facial expression for this sign?
Facial expression is extremely important! In ASL, your face conveys the tone and intensity of the word. When using this sign, your face should reflect the emotion behind it, whether that is anger, frustration, or sarcasm.