Is the closure of the image of $\mathbb C^n$ under vector-polynomial map is irreducible affine variety of dimension not higher than $n$?

I work with the subset $Z\subset\mathbb C^m$ which is the image of $\mathbb C^n$ under vector-polynomial map $f(x)=(p_1(x),...,p_m(x))$, that is $f$ sends $x\in\mathbb C^n$ to $f(x)\in Z\subset\mathbb C^m$.

Is the following true?

1) $Z$ is IRREDUCIBLE constructible subset of $\mathbb C^m$.

2) the dimension of $Z$ does not exceed $\min(m,n)$

3) the closure of $Z$ is the IRREDUCIBLE variety of dimension not high than $n$?

For 1) I know that the constructibility of $Z$ follows from the Chevalley theorem and the irreducibility follows from the fact that $f$ is a continuous map.

Statement 2) is intuitively clear, but I do not know how to prove it.

For 3) (if it is true) I have no any ideas.

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For $3$, did you know that the closure of an irreducible topological space is again irreducible? –  Jim Jun 13 '13 at 17:08
For 2, see this related question: math.stackexchange.com/questions/95670/… –  Yuchen Liu Jun 14 '13 at 4:52
Thank you @Jim, I did not know the fact. I am reading this part of topology now. –  NLHDOW Jun 14 '13 at 16:25
Thank you for the link @YuchenLiu, I will try to post my answer on all tree questions later. –  NLHDOW Jun 14 '13 at 16:26