As for number one, that's just throwing away the first line. It's just the normal readline diamond operator in void context (technically the scalar is superfluous, but I put it in out of habit). The return value is being discarded rather than being saved anywhere (my $toss = <CUR> would have done just the same thing with a (useless) temporary).

As for the data structure, it's a hash of hashes. The top level hash (%data) has keys that are the primary key from your data file (the names), and the corresponding value is a hash of key/value pairs from the various data files. Add something like the following to the end of the program and you can see what it looks like:

...
use Data::Dumper qw( Dumper );
print Dumper( \%data );
[download]

See also perldoc perldsc.