CBSE 12th

You can go for ethical hacking, web designing, animation designing, hardware research, software engineer, game maker and many more option are available, you can check it.

You can go for B.Com+CA, BBA+MBA or B.Com+MBA.

No, you can't do B.Tech after class 12th Commerce. To pursue B.Tech, you should have passed class 12th PCM.

AIIMS is the topmost college for MBBS, then you can go for NEET colleges such as Moulana Azad, Lady Hardin Medical College (only for girls), VMMC, UCMC ( New Delhi), BJMC-GUJRAT, Grant Medical College (Mumbai), PGIMS- Rohtak (Haryana), SMS Medical College (Rajasthan). If you can't score well in NEET exam, then you can go for private colleges. Except MBBS, you may also go for BDS, BHMS, BAMS etc.

Kendriya Vidyalaya, DAV, etc.
These schools are reputed and provide good education also.
Delhi public school is also good in terms of education and discipline.

As per your query, you may consider these options:
Psychology
English Hons
Philosophy
Sociology
BALLB
Foreign language
International relations
Social work
Special education

Take the entrance exam for the course which you want to pursue and wait for your result.

Apply in Delhi University.
They conduct entrance exam also.
But, if you have very good percentage like 90+, then apply for merit based entrance.
Good luck.

If you are from Science stream, you can pursue B.Tech (if taken Maths), MBBS (if taken Biology), B.Tech in Biotechnology (if taken both).
If you are from commerce, then opt for B.Com etc.
If you are from arts, then opt for BA.