Canada

Your question is not clear. Are you asking about Masters in Canada after you have done engineering here in India?

You can do anything, as long as you have the marks and meet with any special requirements. Most institutions offer anything between 40-200+ courses. It's up to you to choose from the options. You haven't mentioned what level you want to study - UG or PG.

No, a few require 6.5 but you should be able to get through as most of the colleges ask for 6 band.

Yes, you can. As long as you have fulfilled the conditions that caused the earlier refusal.

Yes, you can pursue B.Sc in nursing from Canada.

Dentistry in Canada is a second degree which means that you can't study of after doing your 12th here. You have to do your Bachelors in Canada (preferably in biological or medical stream), then clear the competitive exam, interview, etc.

You can give any one. Both are accepted. But if you are applying to an SPP college then IELTS is preferred.

Everything is possible but that does not necessarily mean that it is probable. That's the short answer. Long answer, yes, it is possible as long as you meet the required criteria for PR. However, chances are that you will not meet their criteria and so it may not be possible for you. For the criteria details log into IRCC/ CIC website:
http://www.cic.gc.ca/english/immigrate/INDEX.PHP