IELTS

You must ask the college where you're applying. Email and ask them if it is mandatory for them. Even if they say IELTS is not important to them, the visa issuing Embassy might still require you to write IELTS.

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Hello Shashank,
Scholarships for MS in US universities is a challenging task. There are many conditions to fulfil. There are many nuances to this and if you miss out on any one it becomes most difficult to recover. I would therefore sincerely advise you to approach specialist agency dealing in sending students abroad particularly to US for desired results.
Best wishes

In IELTS each module must have 5.5 band and not less than 5 band to study in Canada. If you have no gap more than 2 years, you are eligible for the best university in Canada. You have 7 bands, I think this is the best score to enter in the university to study MS courses.

Yes, you can definitely give IELTS exam to start working for a firm abroad. Please refer to the link mentioned below for details on IELTS which should help to clear all your doubts and concern. All details including types of IELTS, the need to appear for IELTS, etc. are mentioned in the article posted on the link below:
https://studyabroad.shiksha.com/exams/ielts

I guess you should not face any problems as you have already cleared your backlogs. Moreover, you have a high GRE score and 3 years of work experience.

With your undergraduate score, you will need to have an amazing GRE score, good recommendations and a terrific SoP. I would encourage you to work hard to score 317+ in GRE. IELTS is just a measure of your English proficiency and nothing much. A score of 6.5-7 or above is good enough. You need to work had on other aspects of your application.

You have to give your exam as soon as in September so as to go there in January intake, because the process of Visa and offer letter is very complicated and time consuming.