First about your foreign coursework...
AACOMAS (DO) states:
Other Foreign Transcripts: Coursework taken at foreign institutions must be evaluated for U.S. equivalence by one of the following evaluation services, and an official copy must be sent from the service directly to AACOMAS. You should also have a copy sent to you for completing the AACOMAS application. Request a course-by-course evaluation and list the courses, subject codes, semester hours, and grades on the AACOMAS Colleges and Coursework application page, following the instructions. Your application will not be complete and cannot be verified without an official evaluation. Transfer credit appearing on U.S. institution transcripts, student copies of an evaluation or other foreign evaluations will not be accepted.
You should contact one of the following:
World Education Services
P.O. Box 5087
New York, NY 10274-5087
(212) 966-6311
http://www.wes.org
Josef Silny & Associates, Inc.
International Educational Consultants
7101 SW 102 Avenue
Miami, FL 33173
(305) 273-1616
http://www.jsilny.com
Educational Credential Evaluators, Inc.
P.O. Box 514070
Milwaukee, WI 53203-3470
(414) 289-3400
http://www.ece.org
International Education Research Foundation, Inc.
Post Office Box 3665
Culver City, CA 90231-3665
Phone: (310) 258-9451
http://www.ierf.org
American Association of Collegiate Registrars and Admissions Officers (AACRAO)
Foreign Education Credential Services
One Dupont Circle, NW, Suite 520
Washington, DC 20036-1135
(202) 296-3359
http://www.aacrao.org/credential/individual.htm
All institutions attended (including foreign institutions)
and all coursework must be listed on the Colleges and Coursework page of the application form. If there are extenuating circumstances prohibiting this evaluation, you may request a waiver of the requirement of this evaluation. The letter must state the reason why you are requesting a waiver of the evaluation and must include your signature and AACOMAS ID number. Also note that transfer credit awarded at U.S. institutions for foreign courses will not be added to your Applicant Profile. Failure to submit a foreign evaluation or letter requesting a waiver (which is duplicated to your schools) will result in your file being incomplete. Questions should be directed to AACOMAS.
AMCAS (MD) states:
Independent Attendance, Transferred
Courses attempted independently at a foreign institution must be
listed if the credit has been transferred to a U.S. or Canadian
institution using a credit hour system convertible to semester hours.

Include the foreign institution and the U.S. or Canadian
institution accepting transfer credit in your list of colleges
attended.

Request a transcript exception for the foreign institution.
Indicate the U.S. or Canadian institution on whose transcript
these transfer credits will appear.
 List foreign course work under the foreign institution at which it
was attempted.

If transfer credits are not assigned to individual courses,
subdivide the credit hour total as appropriate and assign credit
hours to each course.

If the U.S. or Canadian institution awarding transfer credit
provides letter grades (e.g., A, B, C, etc.) [FONT=Verdana+Bold0]and .credit hours
convertible to semester hours for [FONT=Verdana+Bold0]each .course on their transcript
or on an official letter [FONT=Verdana+Bold0]attached .to their transcript:

Enter all required course data.

AMCAS will include this course work in AMCAS GPAs,
regardless of institutional policies.

If the U.S. or Canadian institution does [FONT=Verdana+Bold0]NOT .provide letter
grades other than Pass/Fail:

Indicate "Pass/Fail" as the Course Type and provide all
other required course data, entering the transcript grade
exactly as it appears on your official transcript.

AMCAS will NOT include this course work in AMCAS GPAs;
however, AMCAS will include this course work in cumulative
Pass/Fail - Pass and Pass/Fail - Fail credit hour totals.
Independent Attendance, Not Transferred
Courses (other than M.D. course work) attempted independently at a
foreign institution are not required to be listed if credit has NOT been
transferred to a U.S. or Canadian institution EXCEPT to meet medical
school prerequisites unduplicated by other listed course work. If you
include this course work on your application:

Include the foreign institution in your list of colleges attended.

Request a transcript exception for the foreign institution.

Do not send foreign transcripts or certificates to AMCAS.

Provide all required course data except credit hours attempted
and AMCAS grades.
The course work will NOT be verified by AMCAS and will NOT be
included in your AMCAS GPAs.
[FONT=Verdana+Bold0]Although foreign transcripts are never required for the primary
(AMCAS) application, individual medical schools can request
the transcripts to complete secondary applications. Therefore,
you should check with your intended medical schools about
.
[FONT=Verdana+Bold0]their requirements and, if necessary, request your foreign
transcripts as soon as possible.
Is my age and dental background going to be an issue ?
Your age an dental background should not be an issue. Many adcoms may want to know why you are changing careers from dentistry to medicine.
What is the earliest time that i can finish the pre requisites?
This all depends on whether or not your sciences from asia are accepted. If NONE are accepted, it will take you approximately 4-5 semesters to complete all of your pre-reqs (because most schools require the chemistries to be taken in order, and not at the same time... General Chemistry I, General Chemistry II, Organic Chemistry I, Organic Chemistry II, and Biochemistry (Biochem is required by only a few schools).
Is it worth even considering getting into med school given my age and background and low GPA?
This is a personal question that you will have to ask yourself. Personally I believe that it is worth my time and effort (I am 30 with a GPA lower than yours). IMO your GPA is definitely very competitive for DO and MD. The better indicator will be your performance on the MCAT. Just remember that DO schools generally tend to be more sympathetic to non-trad applicants.
I wish you the best of luck!
.