Resume tips for internal promotions?

Okay, I'm shamelessly taking advantage of this blog by asking, but if I can gather some good tips hopefully they'll be of use to others, too.  I'm applying for an internal promotion and need to submit my resume, and I have no idea what I'm doing!  I've never been in this situation before, but I'm sure many of you have (and some of you are veritable career-advice gurus!).

What are the differences between a resume designed for an external employer and one for your current employer?  Are there any pitfalls to avoid, or things to take advantage of?  Or should I be following the standard resume-prep approaches and not treating this any differently?

(FYI, the new position is basically my current job with "Senior" tacked onto the front of it-- it has many of the same core responsibilities, but also involves more leadership, independent decision-making, and input on big-picture strategy.)

I've always felt a little uncomfortable with the "I'm so great" aspect of resumes.  Obviously I want to highlight my accomplishments and put the best possible spin on them.  But I have a hard time figuring out where the line is between phrasing things in the most impressive manner and overstating my case.  And I feel especially sensitive about this since it's at my current place of employment; I keep imagining them reading the resume and thinking "Whoa, she's full of herself.  Yes, she was involved in Project X, but I wouldn't say she 'played a key role.'  She says she 'proposed and initiated important projects in her department' but some of those ended up being a waste of time. Sure, she 'helped train and integrate newer colleagues Y and Z' but they're quick learners and I don't think she made much of a difference."   So I feel like I will then end up leaning towards understatement, which is probably also not the right move.  Any tips on finding the right balance?

Also, I wonder how much I should focus on the aspects of my performance which are relevant to the new responsibilities (i.e. leadership-type stuff) and how much I should talk about my success in other areas of my job which I would continue to be responsible for.  Should I act like I'm applying only for the part of the job that's new, or include the brag-worthy work I've done on things in my current job description?

(And tangentially, since I'm still in my first full-time job out of college, should the resume be entirely focused on what I've accomplished in this job?  I assume I should stick with the functional-resume format, and I'm guessing they don't want to hear about what I did in college anymore.)

Share your experience and your wisdom, and I will listen avidly, I promise!  And in an effort to keep this from being entirely take-take-take on my part, here's the only real article I found about this issue, so if you're in my shoes, take a peek.