Hey terp,
I think my resume is some hybrid of Tuck and Chicago's... but it's good that you're using it as a baseline. I would probably tweak it a little (combine with other schools' formats) so you might not give the impression that Tuck is your #1 school when you apply to other schools (I think they all know what each other's formats are).
terp06
1) Should you list your undergraduate cumulative or major GPA on your resume?
You're overthinking a little.

List it if it's very strong, don't list if it's just average. I listed my UG GPA, which was very good, but didn't list my graduate. Show off your strengths, and listing GPA for an application is not something to worry about if it's strong.
terp06
2) Should you list undergraduate extracurriculars in the education section on your resume? I personally have 5 extra-curriculars that I wanted to list for undergrad - but I barely see anyone listing more than 1-2 at the most on the Tuck book.
I listed 1 or 2 things for UG and Graduate ECs. I wouldn't go up to 5. prioritize and list the ones that are most important. The ones that you fill out in your application (usually they only give you space to put in 3-4 ECs for each school) should be the ones on your resume. Remember, your resume is not a comprehensive work history list. It's a "highlight" that will give someone a good idea of your strengths in under a minute. 1 or 2 things will be enough.
terp06
3) If you can't list your extracurriculars in the education section - do they belong in the Personal section? Again, if so, how many extracurriculars are reasonable to list?
for personal section, I just listed 5-6 things in one line, like "tennis, traveling, photography..." I also had another line for volunteering activities. That's it, 2 lines at the very bottom. Don't list more than 5-6 since it starts to sound like a laundry list.
terp06
4) For work, I currently have 8 bullet points under my current job (i've been here for 1 year, will be 2 years at matriculation)
and I have 5 bullet points for my first job (I was there for a touch over 1 year). Is this reasonable? Should these be condensed?
again, if it's SIGNIFICANT, then 8 bullet points is ok. I had 3 bullet points for each phase of my jobs (I worked at the same company for 7 years), except my first project which took 3 years, I had 6 bullet points. 8 may be a little too much, especially since you've only worked for 2-3 years (13 bullet points if you combine your first job). I would probably PRIORITIZE down to 5-6 for the current job and 2-3 for the first job. I don't think any of us have done so much that nothing can be omitted from our resumes.

terp06
5) Given I will only have 3 years of experience at matriculation - should I list my internships during college? If so, where do they belong?
Internships should only be listed if they show significant leadership or accomplishments. Otherwise, I would just save space to focus on the details and results of your 3 years of full time WE. If you have to list internships, put it at the very bottom of the work experience section, since it's in reverse chronological order.
terp06
6) I am currently using font size 10 for most of the resume, font size 11 for my address/contact info, and font size 16 for my name. Is this reasonable?
Over-thinking a little

. I used 10 pt font, Times Roman for mine, 14 pt for name. It really doesn't matter if it's readable. I know many here on the boards will caution against going below 11 pt font, and in your case (with only 3 years of WE), I would say 11 pt or 12 pt would be more appropriate.
terp06
7) Should you list the months and years of your employment, or only the years? In the Tuck book, it seems that everyone only lists the years, but I have been told in the past that you should always list the months as well. What is proper here?
I list the months based on the template I found, so I would do something like "April 2006-June 2007".
terp06
Thanks in advance for your input guys! Let's tackle this together without the use of an admissions consultant

keep it simple, keep it IMPORTANT, and remove extraneous stuff, no matter how much you want to include it.

I can give it a review if you like, just email it to me.
K