In Angular, the primary module responsible for enabling routing functionality is RouterModule. This module provides the necessary directives and services to set up and configure routing within an Angular application. NgModule is a foundational module used for structuring Angular applications, and RoutingModule is not a standard Angular module.

In RxJS, a Subject is used to multicast a single source (Observable) to multiple subscribers. It acts as both an Observable and an Observer, making it suitable for multicasting.

The canLoad route guard in Angular is used to prevent lazy-loaded modules from being loaded at all if the guard condition is not met. This is useful for scenarios where you want to restrict access to a module based on certain conditions, such as user authentication.

The NG_VALUE_ACCESSOR token in Angular is used to provide the value accessor for a custom form control. This token helps Angular identify and connect the value accessor (typically, a ControlValueAccessor implementation) with the custom form control, enabling two-way data binding and form control interaction.

Implementing the ControlValueAccessor interface for a custom form control allows it to fully integrate with Angular's Forms API. This integration is essential for creating custom form controls that work seamlessly within Angular's reactive forms, enabling features like form validation, form submission, and interaction with ngModel.

In reactive forms, you use the addControl() method to add a new control to a FormGroup. This method allows you to dynamically add form controls to a FormGroup, which can be useful when you need to create form controls based on user interactions or other dynamic criteria.

You can manually request a change detection cycle for a specific component by using the ChangeDetectorRef service. This service allows you to access and control the change detection process for a component. You can call methods like markForCheck or detectChanges from ChangeDetectorRef to initiate change detection. Defining a custom strategy or triggering an event on the element aren't standard methods for manual change detection requests.

In template-driven forms in Angular, the NgModelGroupDirective is used to group controls and aggregate their values and validation status. This directive allows you to manage the behavior and validation of a group of form controls within a form. The other options are not used for this purpose in template-driven forms.

The primary drawback of using the default change detection strategy in larger Angular applications is slower performance. This is because the default strategy involves frequent checks of the entire component tree, which can become a performance bottleneck as the application grows. Developers may need to switch to alternative strategies like OnPush to mitigate this issue.

The fakeAsync testing utility in Angular provides the tick function. It allows you to simulate the passage of time in a test, particularly useful for testing asynchronous operations like timers and HTTP requests.

The 'Access-Control-Allow-Origin' header is crucial for enabling Cross-Origin Resource Sharing (CORS) when making requests to a different domain. It specifies which origins are permitted to access the requested resource, allowing for secure cross-domain communication.

The primary command to create a new Angular application using Angular CLI is ng new. This command initializes a new Angular project with default settings, including the necessary files and folder structure.