Module development and code questions

Hi friends

i'm building a new site on drupal 8, but now all my content type is on drupal 7, 

so the question is, how can i export all my content type and its content from drupal 7 and import on drupal 8?

i was thinkig to creare a xml file and read that file and save my content, but i dont know if there is another way to do that.

Could you please help me?

Regards

When I add custom twig template for my custom form it gives following error

Symfony\Component\Routing\Exception\RouteNotFoundException: Route "" does not exist. in Drupal\Core\Routing\RouteProvider->getRouteByName()

My form buildForm is like this

This is not working for some reason. The form is redisplayed but the textarea field remains empty. Why?

I've installed Drupal 8, I've created a PHP file to read a XML file and insert some items, but I'm getting this error.

Fatal error: Uncaught Error: Class 'Drupal\node\Entity\Node' not found in C:\xampp\htdocs\drupal8\migracion.php:12 Stack trace: #0 {main} thrown in C:\xampp\htdocs\drupal8\migracion.php on line 12

This is the code I am using.

Hi everyone, 

I have a content type "sale" with a field "date", and I would like to delete node automaticaly when date is more thant 7days after now.

Rules en Drupal 8, is a nightmare for me ! I tryed to make a custom module but it's not a success...

Do you have a solution for me ?

Thank you so much for your help !

Just like how the views uses little twig based input field, I want to do the same for my mail message body.

I've copied the form code over from the core->view module, but I am not sure how to set a set of fields to be available to use.

I also tried to use the {{ druapl_field('field_name','node' node_id) }} but this doesn't seem to be working.

Is there a way to set which fields will be available as a replacement pattern or make the function above to work?