Hey there and thanks for posting,
First of all, congrats on that beautiful GMAT!! That will help a LOT when you apply.
Now on to your questions:
It's great that you found what you want and want to move into banking, but I question the wisdom of presenting such a goal to the AdCom. Probably the most common Indian profile I see is "Tech wanting to move into banking." The only problem is that it's not convincing, plus the schools have hundreds of banking applicants with great experience... why should they choose you???
Now, I don't know that you NEED to have banking experience before you apply, although if you want to go into banking post MBA it can be VERY helpful if you can get the job. Actually your job now is to GET IN, so you need to choose goals which are best for your application. My opinion is that if you were to apply with goals in sales/product management/marketing, in which you already have vast experience, you will be presenting the AdCom a far more attractive candidate, because your goals will be so much more realistic.
Don't even think about retaking the GMAT!! It's ridiculous - you already will have the highest score of wherever... instead use your time for other things - like taking on more leadership, getting more involved in volunteer work, organizing a fundraiser, leadership activities - all of these will be MUCH more effective in boosting your profile than a few more points on your already ridiculously high GMAT!!!
Your GPA is a mark against you, no doubt, but you have already done the best thing you possibly could by scoring a 750 on your GMAT. IF you have an explanation for why your GPA is so low, then you can consider writing it in an optional essay.
Voila! I hope I answered all your questions, and if not, feel free to ask more!
If you like the post, give it a KUDOS!