Les expressions negatives...a question about using the negatives in French!!!?

Question

We're learning about the negative expressions in class right now...

My teacher was explaining that personne and rien can be used as subjects. However, I was wondering if you can help me with some of the questions. I think I got it, but I'm not quite sure I'm doing it right.

The questions are:
1.) Est-ce que quelqu'un vous a tellephone dans l'apres-midi?
2.) Est-ce que quelque chose d'important a disparu?
3.) Est-ce que quelqu'un est venu reparer l'electricite recemment?
4.) Est-ce qu'il y avait quelque chose de grande valeur dans votre appartment?

Are these answers right?
1.) Non, personne ne m'a telephone.
2.) Non, rien n'a disparu.
3.) Non, personne n'est venue. (<--does past participle of venir suppose to be venue, since personne is feminine?)
4.) Non, il n'y avait rien. (Or is it "Non, rien n'a disparu.")

I wasn't really sure whether or not to add ne/n' before the a/est...

Answer 1

1.) Non, personne ne m'a téléphoné(e).
2.) Non, rien n'a disparu.
3.) Non, personne n'est venue.
4.) Non, il n'y avait rien. In this sentence, it is hard to use rien as a subject unless you add a verb that was not in the question, like you did : Non, rien n'a disparu.
But you could also say : non, rien de bien important or non, rien de grande valeur

You have to write the ne or n' but nowadays when we speak we tend to forget them : non personne m'a appelé. It is wrong but still we say it. It is a bit like you when you say gonna or wanna. It is not really correct but you use it.

But in you case, put the ne and n'

Answer 2

Your answers are correct.

For number 4, both of them are correct, but they have different meanings:
Non, il n'y avait rien (No, there wasn't anything)
Non, rien n'a disparu (No, nothing disappeared)