Nexus 5 or...

[yfan]

6) I do not know how to set on Android the following work email address. Can you help me? From pc, I have to digit (example) www.dareius.mail.com - Then I type my password and log in. How should I setup my Android phone? Can you suggest me a good email app? I only have 2 email addresses, one on Gmail and the other is that one. Please, help me to setup it. Thank you.

You are telling us how you check your mail on the web. That's fine, and you can do the same by opening up a browser window in any Android phone. But since you're looking to use an email app, you have to be using either POP or IMAP. I assume you know how to set that up for your email. Assuming that is correct, K9 has a great reputation for being a good email app.