1.A cover letter is really your first introduction to a prospective employer.  You are trying to convince them that your the right fit for them to consider further – you want them to give strong consideration to your resume (generally enclosed) or to your job application.  The cover letter is not just a rehash of your resume, it should be in a tone and form to convince a hiring manager to read all of the detail that your resume provides. 

Please submit a cover letter here!  This is a formal letter – it should be addressed TO A PERSON, not just "To Whom It May Concern".  Ideally, it's a real person for a real job that you've found posted, but even if it is not, you should address it to a fictitious person with a full-blown name, inside address, etc. just for the practice.  This is a letter, not a memo.  

2. 

A resume – in paper form as you create here, or in digital form on a site such as LinkedIn – is a vital tool for summarizing your skills and showing your professionalism.  This is true for first-time job seekers and for experienced pros.  Often, you'll find that you'll customize (a little or a lot) each resume you send out – to make it more focused on the job you are seeking.  A resume is a living, dynamic document – you'll need to/want to update yours regularly, even if you're not actively looking for a job.

Your resume may be in a functional layout, a chronological layout, or a combination of both!  Be sure to utilize resources such as your campus career services expert, your advisor or faculty advisor, and others, to help to determine the best resume layout and content for you.