Did Mexican President Pena Nieto also insult Trump when he compared him to Mussolini and Hitler?

No...it's an apt comparison.

Yes. "Building a wall" isn't the same as "setting up concentration work camps" and "invading Poland".

Yes he did. And I think Trump's willingness to start a dialog after such a comparison shows that he has the ability to lead.

  Couldn't agree with you more.

No.....You cannot insult a ego-maniac  who is delusional !

Possibly, but he wouldn't be the first to make that comparison, nor will he be the last, nor is it inaccurate.

http://www.excelsior.com.mx/nacional/2016/03/09/1079807

Obviously, Spanish language newspapers are not a thing he reads.

The fact that Trump never tweeted about it shows that he probably wasn't aware of it, probably because he doesn't understand Spanish.