How do you add a new link into the My Account sidebar?

What are two functions of a resource model? (Choose two.)

Which method of a Magento resource model will remove a record from the database?

You are working on a project that contains a million SKUs. The merchant has requested the product view page to have a custom color schema and page layout depending on the product price range.
How do you implement this, keeping simplicity in mind?

You are developing a module and need to add another column to a table introduced by another module MyCompany_MyModule via db schema.
How do you do that?