JEE Scores

No, 12th marks are not to be added in JEE Mains score.

As COEP is a government college, the admission process is only through the CET marks. They don't take admission through JEE marks.

It's tough to get an NIT with just 49 marks. Well, keeping the difficulty of JEE 2018 in mind, maybe, you can make it into an NIT but branch may not be good.

There are decent chances for you to get a GFTI institute (Government Funded Technical Institutes) along with Some NITs as 150 score is considered as sure seat in NIT. But if you are scorjng well you will got a lead in GFTIs. Don't Worry. All the best for future.

If you belong to reserved Kotak, then you only need to show is your category wised ranking. Many colleges seek admission on the basis of all India ranking but the traditional way is according to your category wise ranking.
Best of luck for your future!

Depends on your rank. If your rank comes around 1000-1500 in general PWD, you may stand a chance. Chances are less for old NITs but you may get a seat in the new ones.

You can get admission if you have a very good score in MHCET.

Sorry, but don't think you will get a government college, but you can try some other university examination.

You should be between 3k to 5k to get admission in IHM-Mumbai in 1st round. And for 2nd round, you must be between 5k to 7k. I suggest you to not join IHM-Mumbai or any other hotel management course, better do simple B.Sc.
I am writing this because, I got IHM Mumbai in 2017 in 1st round of counselling, but after reporting IHM Mumbai, my mindset changed by seeing the scenario of the hotel industry and withdrew my documents and seats on the second day after that.
Currently, I am preparing for Engineering competitive exams.

Yes, you can get admission in that college but you can face some problem if you don't have home state quota.