French sentences

1. Si c'est le contraire, vous me ferez le plaisir d'être ici chaque jour.

You are right, it is faire plaisir à qn de inf, do something Things make someone happy. More polite and courteous than asking you to do something. So the meaning is:

If that is not the case, please stay here every day.

For example, Faites moi plaisir de m'envoyer un message. Please give me a letter and I will be happy. Note that this may also be irony or sarcasm.

2. le jour où la mort vous prendra quelq'un de votre famille

This sentence is incomplete, only the adverbial part. On the day when death takes away someone from your family . . . .

prendre qn, to pick up, take, marry someone, or even rob. . .

It is not prendre qn la mort, la mort is the subject.

3. What does Vous voilà prévenir mean?

This should not be the original verb, it should be Vous voila prevenu(s.es).

You, you, you (women) now have a notice.

Because voila is equivalent to a verb and should not be directly followed by the original verb.

Is this okay?