Colleges in Canada

You need 6 bands with no less than 5.5 after class 12th to study in Canada. To be very honest, even if you get an offer letter from college or university, still visa officer will not grant visa because of low score in IELTS.

You need to take and clear an IELTS test with 6 band, not less than 5.5 in each module.

Approximately 15-30 days.

Hi Parmar,
You can apply, if you meet the admission requirements. In regards to the backlog, this depends on how selective the university is and your overall profile. Though, backlogs are not recommended and Canadian universities are very competitive if you improve your grades and profile significantly, you may be considered.
I hope it helps.

You should be able to. You can write to the college to confirm your eligibility as only the admission officers can tell you the best options for you.

The process depends on whether, you are applying to undergraduate course or postgraduate. So, please mention the level of your desired course.

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.

There is no average salary figures anyone can provide you. The reason being that the kind of job you will get after finishing the course will depend on how good or bad you are at your course.
You can check the college's website here to get more information.
http://www.sfu.ca/career/WCID/faculty-of-applied-sciences/comp-sci.html