Indian Institute of Technology, Delhi

Dear Manik
You have a whole year and above all the realization of not focussing well earlier, if you really wish and determined you can make up for the time lost. Start from 11th and 12th ncert books and practice the concepts thoroughly.
Make a study time table to devote time to each subject.
Identify your learning style and work accordingly.
Be attentive and motivated in your coaching classes to learn.
Dont hesitate in asking questions to ur peer group/ teachers.
If you are really passionate, you will sail through.
All the best and feel free to post your queries.

Top 100 for IIT Delhi.

MAT scores are valid for one year

Teaching is interesting and very detailed.Labs are ok.

u have to come under 700

Cut off and rank varies yearly depending upon number of students appearing in the examination, difficulty of exam and the highest marks scored, so to predict minimum rank is not possible, maybe you can check last few years rank and have a rough idea about the same.

Sure, you can. Go for it.

Marks may depend on the year.A rank upto 5000 will be good to go.

Rank upto 5000 for getting CS.

If by free seats you mean the one that are left for spot round of counseling then that may vary from university to university and there is no spot round for IITs for others NIT you may get admission in 80,000 rank as well but you need a high rank to get into a decent NIT for that rank up to 15000 would do depending upon the trade you are interested.