C'était trés bien
You can say "Elle est très gentille et douce" in French. This phrase conveys that she is both nice and sweet.
très jolie musique
"C'est très bien ici"
You don't, it's never a pleasure meeting somebody who's French.
"vous avez un corps magnifique"
Ses amies sont très polies.
Gracieuse dame (but it's very very old school)
i would say no, someone who isn't very nice might not respect, or treat you well. and someone who doesnt do well in school, but be able to use you to get better.
you say 'agréable'.
Vous êtez tres (good) bien or (beautiful) jolie
passe une bonne Saint-Valentin (very odd thing to say in France)