That's because making a reference of a list generates a list of references:

print Dumper \( 1, 2, 3 );

#output:
$VAR1 = \1;
$VAR2 = \2;
$VAR3 = \3;
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QUESTION 2: is there any other way to generate an array reference (not a scalar references) by picking a selected data to be referenced from an array? (what happens when @_ is replaced by a scalar variable, it only gets the first index from the array slice)

I don't think you can make a reference to an array slice, but I'd be happy to be enlightened.

QUESTION 3: how come it happens that creating a new reference also creates a space in my meomory based on that program?

Sorry, I don't understand your question.