Chemical Engineering

Whichever you find interesting. A relative of mine did Chemical Engineering and got placed in Infosys. A friend of mine did Aeronautical Engineering and is now jobless. If you are planning for MS in some foreign country like the US then Aeronautical Engineering would be a good option. So, choose wisely, after all, it's your future.

Yes, might be. You can check this college prediction link so that you have a rough knowledge of getting a college with this rank:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor

Yes, you may get any autonomous college for chemical engineering with this score.

Chances are conversion is less as you don't belong to state quota. But still you can take a chance and wait for the final list. Cut-off will be different for different years.

1. PSG College of Technology, Coimbatore
2. Shanmugha Arts, Science, Technology & Research Academy (SASTRA University), Thanjavur
3. Thiagarajar College of Engineering, Madurai
4. College of Engineering, Guindy, Anna University
5. Amrita School of Engineering, Coimbatore.

Hello Aranyo,
I am attaching a link for your query. Please go through it. I hope it'll help you finding the appropriate choice:https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor?utm_source=connect&utm_medium=CR_JEECP&utm_campaign=7576872
Good luck.

Which CET? You haven't mentioned. Anyway, the chemical engineering seats are very limited and always students in the top rank will get it easily.