I just happened to find your question- I'm sure you've received other responses by now, but I thought I would share my two cents worth with you. I graduated from SCO in Memphis in 1995, and have been practicing optometry for 15 years in Nashville.
To answer your questions- I think you would be fine either way regarding the undergraduate major, as long as you take the courses that most all optometry schools require, you could probably major in just about any of the sciences and meet those requirements.
Optometry is a competitive field, both in terms of admissions (SCO for example has an average of around 650 applicants for 120 seats per entering class), and in terms of financial competition out in the real world once you complete school.
I enjoy what I do, but it can be stressful, and depending on the area you want to practice in, Atlanta for example, it can be very competitive, which may limit your practice opportunities, but in smaller cities/towns, there may be better opportunities.
Third party vision plans have driven down reimbursements per patient, and commercial chains like Walmart have created a lower perception of the value of what we do, but private practice is still very rewarding with the right approach and in the right area.
I hope this may give you some help, please let me know if you have any other questions.
Dr. Alan Ballard