Regarding question 3: Perl does its level best to convert a string to a number in numeric context, as supplied by the addition (not assignment) operator. Example of behavior in this context (with warnings, which you obviously wern't using):

>perl -wMstrict -le
"for my $string (qw(x 1x 12x 987x)) {
   print qq{string '$string' in numeric context is == }, 0+$string;
   }
"
Argument "x" isn't numeric in addition (+) at -e line 1.
string 'x' in numeric context is == 0
Argument "1x" isn't numeric in addition (+) at -e line 1.
string '1x' in numeric context is == 1
Argument "12x" isn't numeric in addition (+) at -e line 1.
string '12x' in numeric context is == 12
Argument "987x" isn't numeric in addition (+) at -e line 1.
string '987x' in numeric context is == 987
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See Scalar values in perldata.