B.Com

To know about the cutoff, placements, fees, admission. pf Master of Computer Applications (MCA) at Ramaiah Institute of Technology, Bangalore, refer to the link given below-
https://www.shiksha.com/college/ramaiah-institute-of-technology-m-s-r-nagar-bangalore-474/course-master-of-computer-applications-mca-406533

No Doon University didn't provide placement in government banks. Infact no institute or university provide direct placement in government bank or institutions. One need to qualify entrances and interview held by government organisations to get into bank.

Yes you're eligible
But you can't do it from Top B schools as they will look for your last academics. But you can do it from decent colleges with a decent package.

Yes, you can do it. As CS requires more time and effort doing B.Com or other graduation through distance mode will be helpful for you. If you cleared your CS every one will hire you on the basis of a CS Certificate so it will not affect you so much. But if somehow you didn't clear your CS B.Com from distance will somehow give us less weightage.

You can apply in IGNOU DUSOL, Narsee morajee, Chandigarh University, Symbiosis, Mysore University
for Distance/correspondence course in B.Com.

In which college or university do you want to take admission. As entrance dates differ from college to college.

If you're interested in marketing and business u can opt for MBA
If you have an interest in accounts u can opt for M.Com. Or any other professional course. If you are interested in Law you can go for LL.B.

No, it depends upon us how we use our education and knowledge. Even if u didn't get any placement u can open your office or start teaching students for CS as CS is some of the most respected professions in India. Every stream has vast opportunities It depends on us how we SEE them and use them. Go for your profession. All the best.

Diploma in digital marketing
Tally
Excel
Business accounting and taxation. These are some short-term courses you can do after your B.Com.

Yes as for B.Ed. You need a graduation degree you can easily get admission after doing B.Com.