Science

You need to write an improvement exam for that, as there are less or no chances for getting admission on that basis.

Minimum eligibility for this course is an Intermediate qualification (10+2) with Physics, Chemistry, Biology and/ or Mathematics as main subjects, so you can't opt of that because you are a commerce stream student.
Hope this helps.

Your marks are very low most of the time the admission for general category closed above 90 and your marks are deducted when the percentage calculated against the cut off released by DU because you are fro. Science background and didn't studied any subject of B.Com. If you belong to general category your chances are very low to get admit in this course. If you belong to ST category maybe you get admission. But don't lose hope; wait till the last cutoff comes. You can check out last year cut off released by DU on their website.

Do B.Tech beacause you won't get the best campus in DU. Consider taking decent government or private colleges through your UPSEE rank.

IP University.
Christ University.
Lovely Professional University.
Amity University.

If you are not interested in Science stream, you can opt for commerce stream or arts stream. There is a wide range of interesting subjects to choose from in arts stream.
But before opting for commerce or arts stream, make sure you are not interested in Science stream as you can't change it back and forth. Do a little introspection.
If you like biology, the medical profession is also highly sought for, just that you have to bear with physics and chemistry for a few years.
Good luck for your future!

Yes, you can do it as some colleges accept it.

Yes, you can do it. Commerce graduates have good options as follows.
M.Sc. Finance
M.Sc. Corporate Finance
M.Sc. International Finance
M.Sc. Banking and Finance
M.Sc. International banking
All Masters programmes abroad are specialised programmes and focusing on a specific field. This will make you more employable.