BJMC

Hi Diya,
Yes, you can. You will have to appear for an entrance exam, after which your admission status will be determined. You can find detailed information here:
http://www.iimtu.com/admissions-procedure

Delhi University does not hold any course named BJMC. It holds three courses in the field of journalism. I.e. - B.A. (journalism honors), BA (Hindi Patrakarita) and BMC (only in IP College for Women) (check DU's website for the colleges that are offering B.A. Journalism honours and B.A. Hindi Patrakarita).
For B.A. (journalism hons) and B.A. (Hindi Patrakarita) there is no entrance, there is proper cutoff range for that. For BMC there is an entrance exam and the topics that are covered in that exam are as follows:-
Entrance's syllabus includes English communication, current affairs and a little portion of static general knowledge.

You cannot do your Bachelor's twice. But, you can apply for Masters in journalism and mass communication. It is the option you should go for (MJMC).

What is your category as admission depends on category only?

Hi Amit!
There are no tips as such. In the counselling process, you will just have to see if your rank is suitable for any college. You will then have to make a decision which college you want to select out of the ones you are eligible for. You will be provided with a form, that you need to fill up with your details, college preference and submit other necessary documents as and when your rank will be called upon.

Hi Utkarsh,
Yes, admissions are based o 12th marks, merit-based screening. Please check details here
https://www.shiksha.com/mass-communication-media/course/bachelors-in-journalism-and-mass-communication-international-institute-of-media-and-communication-salt-lake-city-kolkata-269137

Hi Aditya,
Yes, you can surely get a decent college with this rank. You can expect to get admission in Trinity, Tecnia, Fairfield or Madhubala Institute.

Hi Ritika!
You can expect to get admission in Tecnia, Fairfield, Madhubala or Kasturi Ram. If not in first counselling, you will surely get a seat in second counselling.

Hi Ashok!
Yes, you are certainly eligible for the counselling. You can expect to get admission in Kasturi Ram, BLS Institute or Lingayas Lalita Devi Institute of Management. If not in first counselling, you will surely get a college in second counselling.

Hi Isha,
You have a very good chance of getting a good college in IP University. You don't really have to worry, you have a high probability to get admission in the top colleges like Vivekananda Institute, JIMS, Maharaja Agrasen and Trinity Institute of Professional Studies.