All of those questions will be addressed by user requests.

As for the $errstr and errstr() stuff ... get rid of $errstr and make errstr() a class method. So, of the form:

sub errstr {
    my $self = shift;
    return $self->{errstr} if Scalar::Util::blessed $self;
    return $errstr;
}
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That allows for the possibility of multiple objects.

As for new() failure, the meme is this:

my $obj = CLASS->new( ... ) or die CLASS->errstr;
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