(2) You can see that Perl chooses (a) for /$x{1}/. If I want (b), is there a better way than @{[$x{1}]}[0]?

Absolutely. Quote your hash key.

my $x = "(quantifier)";
my %x = ( "1" => "(hash_value)" );
my $z = 'quantifier hash_value';

print "_$1_\n" if $z =~ /$x{'1'}/;   # $x{'1'} is hash key

__END__

_hash_value_
[download]

Hope this helps.

jarich