Entity Framework Code-First - Defining relationships with MembershipUser

Я пытаюсь понять, как лучше всего определить мои классы POCO, чтобы иметь возможность использовать функцию Entity Framework, ориентированную на код.
I want to define some foreign key relations in my classes, between the user and also between the classes themselves. For example consider the following 3 classes:

Public class Job
{
    public int JobID {get; set;}
    public string JobTitle {get; set;}
    public virtual ICollection<Resume> Resumes {get; set;} // Is this correct at all? How to access all resumes for a certain job? (many-to-many relationship between Job and Employee)
}

Public class Resume
{
    public int EmployeeID {get; set;} // or should it be: public virtual Employee EmployeePerson?
    public int JobID {get; set;} // or should it be: public virtual Job UserJob?
    public DateTime EmploymentDate {get; set;}
}  

public class Employee
{
    public int EmployeeID {get; set;}
    public int UserID{ger; set;} // or should it be: public virtual MembershipUser User?
    public ICollection<Resume> Resumes {get; set;} // Is this correct at all? 
}

The user is a Membership user which is in System.Web.Security which is being authenticated by FormsAuthentication or ActiveDirectoryAuthentication. The questions are mentioned in the code (as comments). But for clarification:

• Should I define the objects in relations and use .Include every time I need them or is it better to store the ID of the objects and try to get the data from that ID every time I need to? Should I use a different approach when dealing with MembershipUser class instead of my defined classes?
• What's other uses of virtual apart from enabling lazy loading? Where should I avoid it and where should I use it?

Thank you.

UPDATE: I have just tested to define Employee with the ublic virtual MembershipUser User definition. The result was 4 added columns in my table:

• User_Email,
• User_Comment,
• User_IsApproved,
• User_LastLoginDate,
• User_LastActivityDate

Nothing unique to the user (User_Email is defined as nullable). So If you want to have user in you classes, write a wrapper for MembershipUser or just store UserID.
Спасибо, Ладислав и Серги.