Incorrect English. One does not say : they read you. The correct answer is : they read to you
"They read to you a newspaper?" Perhaps correct (?), but clunky. "They read you a newspaper" is more natural, at least in American English.
One does say on the other hand, "They read a newspaper to you."
How can we know its "αυτοι" and not "αυτη"? Sounds the same ?
They do sound the same, but the verb forms will be different, too.
The best English translation is exactly as shown. The secondary translation? "They read a newspaper to you." (I'm a professional legal and scientific editor in English, an English and ESL teacher, and a native English speaker.)
What's the difference between σου and σας? Could σας be used in place of σου? How are their meanings different?
Σου is the singular form, σας is the plural and the formal (i.e. even if addressing only one person) form. Use accordingly. :)
Indication of the used pronoun: