B.Com

Hi Muthupandi, first I will advise you not to discontinue this course as it is a wonderful course. But if you really want to discontinue it just don't give the examination in one semester. You will be declared drop out.

If you had Statistics in B.Com only you can join M.Sc (Statistic ) (minimum 60% marks).
Only a few seats for M Sc Statistics. The first preference is B Sc Statistics or Maths with Statistics. It is unlikely to get a seat in PG statistics for B.Com degree holders.

Maths is not a mandatory subjects in B.Com degree. Top colleges are listed below:-
Sri Ram College of Commerce, Delhi
Hindu College, Delhi University
LSR, Delhi University
Hansraj college, Delhi University
Loyola College, Chennai
MCC, University of Madras
KMC, Delhi University.

Timings are given below:
8:30am to 4:30pm
Lunch break
12:30pm to 1:30pm

It totally varies from university to university. For example, in Delhi university it cost around 15k for one year. So for total duration of 3 years, it will cost roughly 50k. For the private universities it will cost 30-50k for one year. And in total it will cost around 1-2.5 Lakhs.

Yes, any student who has completed their graduation or may be in last year of graduation can apply for MCA. However, Maths should be the main subject in 10+2 or any year of graduation. Students of Arts, commerce as well as of Science stream can apply for MCA.

Yes, you can do B.Com after 12th Science (maths). because Science students can take any field in graduation if the student is from Maths and Science can do B.Com, Maths students can easily do B.Com because maths help them for this.

Yes, you can do after B.Com, as you already have Bachelors degree you can either opt for Diploma in Interior Designing ( 1 Year programme) or M.Sc. In Interior Design considering the fact that you already have Bachelors degree.