"The mouth" is an English equivalent of the French words "la bouche." Specifically, the feminine singular definite article "la" means "the." The feminine noun "bouche" means "mouth." The...
Yes it means Shut your mouth!
My head my head
"oh la la" is not a question but an interjection marking surprise. You don't have to answer it, although you may want to ask a question in turn.
It is an expression of pleasurable surprise or appreciation usually with a sexual motivation.