Drupal 8.x

Hello,

I am trying to manually migrate my D7 site to D8. I am "nearly" there - not a very enjoyable experience!.

In the process I also want to migrate a Flexslider slideshow that makes use of field collections. For the moment I don't really want to migrate to the Paragraph module (as suggested in a couple of Google results...). 

However, when enabling the Field Collection module (version field_collection-8.x-1.0-alpha1), I get the following fatal PHP-error:

I was wondering what is the correct alternative of .inc files in Drupal 8? That is to say, if I want to create some functions that should be only be loaded when required, like it was with module_load_include() in D7. Though this function is still there in D8, I hear that this is not the best procedure. Is that so?

I was wondering if using hook_module_implements_alter() is a good practice in D8 also to alter the order of execution of hooks?

I came to hear that it is suggested to do this with events that was introduced in D8 which will be a better way, but I could not find any reference that says not to use hook_module_implements_alter()in D8. One such ref.

Here is my entity object.

​​​​​​​Payment {#1020 ▼
  #values: array:17 [▼
    "amount" => array:1 [▼
      "x-default" => array:1 [▼
        0 => array:2 [▼
          "number" => "2.43"
          "currency_code" => "EUR"
        ]
      ]
    ]

I need to get the "number" value, but I can't get it easily.

$amount= $entity->get('amount')->getValue();

I get this result :

Hi everyone,
i am new to Druapl, just starting learning few days ago.