Mini-Questions

A few questions, about stuff I am not sure I got right. Sorry if this 
has already been resolved.

- What is the default behaviour (without using any pragma) of 1/0?
  NaN or exception?

- Are these correct? What will they do?

  my Int $i is bigint = 777_666_555_444_333_222_111;
  print $i;

  my Int $i = 777_666_555_444_333_222_111;
  print $i;

  my $i =  777_666_555_444_333_222_111;
  print $i;

- Do Perl programs use a standard-sized platform-indepedent arithmetic 
by default, or do they relly on the native size?

Thanks,

-angel