Answer 1

The Java collection LinkedList stores both previous and following node, so it's a doubly linked list.
It comes with methods to add element(s) to the beginning, end or at a specified index of the list.

If you're asking about a custom implementation, you need to link your code to your question to let us help you.

I don't understand what you mean by the user selects and locates, could you please elaborate?
Also, I don't know why you added the tag dll, that might need some more explanation as well.