There are many different types of components that can be added to a Dashboard in Salesforce. These components include Horizontal Bar Chart, Vertical Bar Chart, Line Chart, Pie Chart, Donut Chart, Funnel Chart, Scatter Chart, Gauge, Metric, Table, Visualforce Page, and S-Control. A Custom Report Type is not a valid Dashboard Component. A Reporting Snapshot is not a Dashboard Component.

There is a feature in Salesforce for Similar Opportunities, which can be enabled and configured to match against fields. This feature allows users to find Closed/Won opportunities that match the attributes of an opportunity they're currently working on, so they can quickly access information that might help them close their open deals. Big Deal Alerts have to do with large opportunities and sending alerts related to them. You always want to avoid resorting to code, such as Apex Triggers, whenever something can be done declaratively on the platform (i.e. Clicks instead of Code), so asking a developer to write a trigger would be more time and cost intensive than simply enabling and configuring the Similar Opportunities feature. Workflow rules can't really pull in matching records. The Process Builder could perhaps fulfill this, but the myriad of possibilities would make creating it very complex. You could also potentially tie in a Flow with a Process to avoid resorting to code, but then again, that would be overly complex and time consuming as well. The main point of my ramblings is that you'll learn there are many ways to accomplish something on the Salesforce Platform. The key is learning which is the best option, given a scenario, and understanding the plusses and minuses of each approach. For more info on the Similar Opportunities feature, refer to

https://help.salesforce.com/articleView?id=customize_oppsimilaropp.htm&language=en_US&type=0.

The values that appear and can be selected in a dependent field are controlled by the controlling field. https://developer.salesforce.com/docs/atlas.en-us.206.0.fundamentals.meta/fundamentals/adg_simple_app_adv_field_dependencies.htm

When you click the Map Lead Fields button from the Lead Custom Fields and Relationships section on the Lead Fields page, you are able to map custom lead fields to custom fields on the Account, Contact and Opportunity objects.

Refer to https://help.salesforce.com/articleView?id=lead_conversion_mapping.htm&type=0&language=en_US&release=206.15 for more details.

It is the Sales Process that determines which stages display on an opportunity. These are specified by record type on the opportunity, so therefore, you would need to create a new Sales Process and Opportunity Record Type to accommodate this requirement.

You can edit a page layout and specify a field as Read-Only, or set the Field Level Security for the field to Read-Only. You actually can also create a Visualforce page that renders as a PDF and display Salesforce format as a Read-Only PDF, but this would make all fields on the page Read-Only, so that's taking things too far. There's no such field type as Read Only when creating a new field.

When you delete a custom field, it is automatically removed from all associated page layouts without you having to manually remove the field from each. It also takes care of removing any Field Level Security Settings for the field.

You can't limit access via a Sharing Rule, but only expand access. You would want to set the Org Wide Default on Accounts to Private, since the best-practice principles of the Security Model in Salesforce dictate that you start with the most restrictive settings, and then you open up further access and rights through Sharing Rules, for instance. You could technically ask one team to manually share with another, but this isn't the best option, when there is an automated way to accomplish this in the system by way of a sharing rule.

You would need to make the app visible to the profile from the Assigned Apps section of the Profile. The App Permissions section of the profile control specific permissions related to standard apps in Salesforce, such as Call Center, Content, Knowledge Management, etc. The Object Settings section on the profile controls the CRUD (Create, Read, Update, Delete) rights and Record Type designations for an object for a profile, but doesn't control app access and visibility. You can also grant access to an app via a Permission Set, but you do not access Permission Sets or assign them from within Profiles.

When creating a custom report type, you can specify either that each "A" record must have at least one related "B" record, or that "A" records may or may not have related "B" records.

Refer to https://help.salesforce.com/articleView?id=reports_defining_report_types.htm&type=0&language=en_US&release=206.15.