Diploma

There is no age limit. You should have your Diploma certificate.

Yes visit to www.amity.edu/lateral before 4th of august and follow the procedure

Only you can answer this as your choice of course completely depends on your academic and work history plus your areas of interest.
Which course would you like to pursue? What is your academic profile and work history?

Any course, you will pursue will have good job prospects, as it all depends on your capabilities to be a great student and employee. If you manage to score well in your course, and get an internship with a reputed company, you will not have any problem finding a good job.

Diploma courses are more technical in nature and degree courses are more theoretical. The job opportunities depend on your skills and subject knowledge. If you are good at your course and score well, then you should have no problem getting a good job with either course.

PGDM from IMT is highly recommended and is the best amongst above colleges you mentioned for brand value, placements and internship opportunity, international jobs, faculty and grooming. PGDM and MBA have equal weightage and both can be done.

Yes you can, you would require to give entrance test for the college you want admission in.

Hi Gagan,
After completing the Diploma, you have the option to complete Bachelor of dental sciences at UBC and a Bachelor of health sciences from TRU. To start looking for jobs, you must acquire a license first, to be eligible for registration and licensure with the College of Dental Hygienists of British Columbia.
Graduates must pass the national dental hygiene certification examination. It is better, if you obtain a Bachelor's degree for better job prospects and later think of a PG level qualification. Please note that programs intake is under review. So, contact the college directly before applying.