CBSE 10th

There is no matter if you had Hindi or English in 10 class. Only 12 class marks matter. Different courses has different criteria to get admission. Because admission process is based on the class 12 aggregate marks of different subject which is checked against the cut-off released by Delhi university for different courses. In which course you want admission.

Hi Aman,
Candidates who have passed 10th Std. / SSC examination and obtained at least 35% marks in the qualifying examination are eligible to apply for the course.
http://ghru.edu.in/polytechnic/mining/

I assume that your wife has not completed 12th exams. So, one needs to complete 12th boards before pursuing any course in any University.

There is a very good chance. Prepare well for GD and written test.

If you want get admission in b.tech mechanical so you can easily apply in any college of b.tech by showing your diploma mark-sheet.
If you have your diploma mark-sheet, then it doesn't matter whether you have completed your 12th or not.

Yes but for getting top colleges you really need to score well in CAT at least above 95 percentile for getting call from top colleges and above 98% to getting call from IIMs.

For normal people, it is around 82% - 85%, but for people with Hindi minority, it is 70%.

Event Management Degree or Mass Media Graduation can take you to a good understanding of Event Management. I believe that it is the College or University Life, which actually teaches such things because you also get to do such even management and more. I shall suggest that you can do class 12th with any stream, be it Science or Commerce or Arts. However, the best Option is Commerce or Arts, so that you have time to develop your knowledge, personality and interest in management of events.

Hi,
Yes, you can apply for Certification of Japanese Language after 10th. Please find the link below for detailed information:
https://www.educationforever.in/college/international-institute-of-language-and-culture-iilc-kolkata

No,
You can go for Diploma. There are many Diploma available after class 10th like Diploma in IT, designing etc.
Good Luck.