Which cycle is preferable for daily commute to office in India?
I'd suggest that you start with a used bike – perhaps the Indian craigslist would be a place to start. You could observe what people are using for commuter bikes in your area, maybe even talk with some of them, and get some ideas about what sort of bike would be appropriate for you. A used bike will be less expensive and you'll lose less money if you decide to sell it and get another bike once you learn what works for you.

Regarding the bag, 10 km isn't too far, if you've got a backpack start with that. You'll probably find that the pack is hot on your back and you may prefer something else – but for starters any bag that isn't too uncomfortable to ride with will get you started. For myself, I don't like having any kind of bag on my back when I ride, so I use panniers – but I have the luxury of feeling relatively comfortable leaving them on the bike for short stops. If you want to get off you bike and go into a store or office with minimal fussing with the bike I think a messenger bag or backpack would be a better way to go.