Dear Tejbir,
To answer your questions:
1. Being an entrepreneur, I do not have any supervisors or employers from whom I can take recommendations. Would it work to my disadvantage if my recommenders are my clients?
No. Recommenders can be clients or vendors whom you have worked with for over a year and that you feel can comment positively and specifically on you as a professional.
2. Is having an entrepreneurial experience a disadvantage vis-a-vis a focussed technical / professional experience?
No. There is no preferred experience in MBA admissions. What will be important for you though is to be sure and highlight the professional accomplishments you have had and the skills you have gained from your entrepreneurship experience.
3. Having more than the average work ex works for or against me because there might be placement concerns for people with high work ex?
While you are over the average for a traditional, daytime MBA program, you are by no means "too old" or at a disadvantage with the amount of work experience. You do need to explicitly address why you want to attend the daytime program though and how it is the right program for you based on your goals. Likewise, you might also note you understand your job search will be different from your classmates as you have more experience.
4. Do I have a competitive profile for Stanford, Booth, MIT, Haas, Tepper, and Darden? Are these schools fine high work experience or are they looking for younger people? Please advise.
All schools, these that you note included, look for the best candidates and admit a range of applicants. While many programs are trending younger, it is important to note the global applicant pool is also trending younger. If you can convey a solid rationale for the program based on your career goals, then you should be competitive for these schools based on the rest of the abbreviated profile you posted. Realize that the ultimate decisions will be based on more than your GMAT, GPA and amount of work experience--your essays, recommendations, resume and interviews will play a significant role.
Good luck,
Lisa