Julia,
I completed 2 residencies - my pharmacy practice and then a specialty in heme/onc. I have been practicing (as a clinical specialist) for the past 2 years now.
Definitely start getting your CV in order. The secret to having a good CV is to update it consistently; don't wait until you are ready to start applying to go back and update; it's so much easier to update as you go. If you publish an article or review, for example, add this to the "publications" section of your CV as soon as you can. As your career progresses, your CV should continue to reflect your accomplishments. Your CV is a living, breathing document, so to speak.
As a pharmacy student, your CV will be relatively short; you would list your rotations and a few details about each. Later on in your career, your school rotations are not as important to the reader as they once were, and can generally be replaced as your work experience and list of accomplishments grow over time.
Have as many people proofread your CV as possible. You'd be suprised at the ones I have seen with glaring errors or inconsistencies. The CV should be perfect! We have rejected residency candidates due to sloppily written or incomplete CV's.
Also, start composing a generic cover letter as well as a letter of intent. As you apply for specific residencies or positions, you then tailor the generic letters to meet the needs of the particular residency/position you are applying for. Contrary to what many people say, letters of intent and cover letters are VERY important. We all have CV's, but what sets your application package apart from others is a strong letter of intent and a succinct cover letter. Cover letters generally aren't required, but letters of intent ARE.
The letter of intent is generally a one-page document detailing your interests, strengths, and what you see yourself doing in the future. In the letter of intent, you want the reader to see exactly what you bring to the table and how valuable you will be to their organization or program (in the case of residencies).
As for how many letters or recommendation are usually required, the standard is three, but you can have 1 or 2 extra (I wouldn't do more than that as too many can become overwelming to the interviewer and may just get your application thrown in the trash).
Hope this helps!
Bonnie