Do initializers get loaded after app folder classes get loaded?

I am trying to debug some Carrierwave nonsense. This is what I understand so far:

I think this code in my carrierwave.rb initializer gets run after the app/uploader files are loaded. The reason why I think that is because my fixture files get uploaded to these directories defined here:

This is my carrierwave.rb initializer:

if Rails.env.test?

  ZipCodeCsvUploader
  StoryMainImageUploader

  # use different dirs when testing
  CarrierWave::Uploader::Base.descendants.each do |klass|
    next if klass.anonymous?
    klass.class_eval do
      def cache_dir
        "#{Rails.root}/spec/support/uploads/tmp/#{object_id}"
      end

      def store_dir
        "#{Rails.root}/spec/support/uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
        # "#{Rails.root}/support/images/#{model.class.to_s.underscore}/#{mounted_as}/#{object_id}"
      end
    end
  end
end

The store_dir and the cache_dir seem to trump this app/uploaded file:

# encoding: utf-8
require 'carrierwave/processing/mime_types'

class StoryMainImageUploader < CarrierWave::Uploader::Base
  include CarrierWaveDirect::Uploader
  include CarrierWave::RMagick
  include CarrierWave::MimeTypes
  include S3DirectUploader

  process :set_content_type

  def store_dir
    "stories/#{model.id}/main_images"
  end

  def cache_dir
    "#{Rails.root}/support/uploads/tmp/#{object_id}"
  end

  def extension_white_list
    %w(jpg jpeg gif png)
  end

  version :medium do
    process :resize_to_limit => [800, 800]
  end

  version :thumb do
    process :resize_to_limit => [200, 200]
  end
end

None of the uploads will hit these files.

So my questions:

1. Do the app files get loaded in a Rails app startup before the initializers?

2. What do the lines:

   ZipCodeCsvUploader
   StoryMainImageUploader
   
   

do? How do we have access to these class names unless the classes were loaded first? Even if we do, what does calling these class names do?