B.Com Preparation

Yes, surely you can prepare for M.Sc statistics. Colleges offering M.Sc statistics are:
Acharya Nagarjuna University
Adharsh Vidyalaya of Arts and Science for Women
Agra College
Aligarh Muslim University
Allahabad University
Alva's College
Amity University

You can prepare for PO exams simultaneously with B.Com. You can join an institute for PO exam preparation but you can attempt exam only in last year or last semester. You can also take weekend classes for PO entrance so that you can manage your B.Com classes also. You have to manage the time between both the courses and also regular practice is needed for PO.

Hi Anushka. It is best that you start your CS alongwith graduation. Managing both CS syllabus and graduation studies is a bit challenging, but can be managed with ease, once started. If you are planning of doing the same with MBA, the task would be a bit more challenging. The only benefit you derive starting CS after graduation is that you don't have to appear for the foundation exam. Think and act wisely. Feel free to revert. All the best!

I think it is the right time to prepare for CAT or CET exam.

It is totally dependent on you. But, if you cannot clear the CAT examination, then B.Com from good institute will help you to generate its job opportunities but doing B.Com from the college where attendance does not matter can't help to generate job opportunities for you.

Hi,
For college entrance exams, the main emphasis on the English language, general Awareness in GK and current events and logistic aptitude. You will find books in book shops related to college entrance exams.