Mumbai

1. Don't worry, look for options, take time and look for good options. Step in something that can help you start or do your business.
2. Would my Commerce counterparts have a upper hand over me?
Ans. Yes, they will only if you do not cover it up, there are coaching centers who provide you coaching & believe me anything you do by heart is easy and then you are from Science you will be able to get everything in that crash course or whatever you do to learn. You will get it, also you can use search engines to learn what you missed read books, consult your commerce faculty of school - I am sure they will guide you.
3. If you really want to do a business start looking for opportunities & courses related to that course also ask your friends and others, scratch the search engines. Look for courses and attend the counselling or any sessions that colleges provide.
4. I don't know what business you want to pursue with but as far as I know, I have my own relatives having business and they were Science students, do MBA or just start doing it or do a job after you are done of your graduation. However, graduation in anything is a must. So, try it out.