Multilanguage

Hi ,sorry for english ,  i see this tutorial to implement multilanguage :

https://www.codexworld.com/multi-languag...deigniter/

I have some question :

can i call directly on view  ?

Code:

<?=lang('message_to_show')?>

or must i create a variabile in controller ?

Code:

$data['message_to_show'] = lang('message_to_show') ;

and in view :

Code:

<?=$message_to_show) ?>

Another question :

If i create several file for language (in every subfolder of language) , How can i import only the file that i need ?

Last question:

how can i change the form_validation error ?can i do this :

Code:

'min_length'=>lang('min_lenght_field')