For Q. 1), you could just grab the remainder of the string:

use strict;
use warnings;

for my $row (
    'MACHINE_CLASS=9000/800/L3000-5x',
    'MACHINE_CLASS=ia64 hp server rx2600'
) {
    my ($machine_class) = $row =~ (/MACHINE_CLASS=\s*(.*)/);
    print "$machine_class\n";
}

__END__

9000/800/L3000-5x
ia64 hp server rx2600
[download]

Take a look at perlre to see what \w matches.