Hello AJYMERCED,
I highly recommned checking out the APTA's information for prospective students:
http://www.apta.org/ProspectiveStudents/ as it holds the answers to MANY questions pertaining the PT education and career.
Anyway, to answer your questions as briefly as possible, it'll take anywhere between 2.5-3.5 years to complete an entry-level Doctor of Physical Therapy (DPT) program. This is a clinical doctorate, not a research doctorate, i.e., Ph.D. The length of the program depends solely on the program you choose to attend. More information about this can be drawn from the specific school's PT website. You may find some Masters degree for PT like in CA, but those are being phased out for the DPT degree. Overall, with a Bachelors, total education for a PT would be approximately (if everything goes right and you enter as a traditional student) 6.5-7.5 years.
However, the vast majority of DPT programs require a Bachelors degree to be recognized as an applicant; there are a few that don't. There is NO specific degree you need, and like medical school, they don't really care if you're a Kinesiology major or a Music Performance major. You will, however, need to complete the specific prerequisites required by the schools, and each school will have different prerequisites for you to take. So you may enroll in any degree plan you want for your undergraduate career. A science major may better prepare you, but it that's not really guaranteed. Just make sure you pick a major you will enjoy (and maybe one that is terminal, just in case for Plan B).
Average GPA for the entering class of 2010 of the school I will attend is a 3.73/4.00, but it is possible to get in with stats much lower, depeding on the school and the other elements of your application materials.
In addition, you need to take the GRE and schools will specify whether they want you to take the old or new version of the GRE. To stay competitive, I'd recommend an 1100 or above at least. 1000 and above, you're cutting it close.
To help your resume? Volunteer, shadow PTs, establish great raport with the PTs that you will have write your Letters of Recommendations for you, as these items are extremely important for your application. Get as much quality experience as you can. Learn as much as you can about the career, why you chose PT, the current issues facing the profession, and where the profession is headed in the future for the interviews.
Decide if PT is right really for you.
Again, I'd advise taking a look at the above link about this. And you can always browse all the threads we have on SDN Physical Therapy. You're bound to find many answers to your questions.
Good Luck.