VGO i would also recommend you visit your nearest indian high commission to clarify the privileges of a PIO. My aforementioned instructor had a chat with his embassy and was informed that he has every right to work in India. There were some restrictions on voting, or becomming president....
Anyhow. First things first. Get 12th maths and physics done. the rest from there shouldn't be too hard. And as i mentioned before you are welcome to contact me if you want anyhelp.