I think you have lots of time to tease this out. At this point, your seventh grader should be allowed to be…a seventh grader. Let him explore ECs that are of interest to him. Try not to pidgeon hole him into anything. Let him try and find his own interests.
To attend college in the U.S. you parents will need to determine what will be affordable for you. Many U.S. colleges don’t provide any aid of any kind to students who are not U.S citizens or permanent residents, even from Canada. So…have a budget in mind.
Don’t forget to look at many of the fabulous colleges IN Canada. There are many, and I’m sure others will comment.
Re: SAT or ACT scores, this is a wait and see. The landscape of these scores will most likely change in the 5 years until your student applies for college.
Right now, you want a happy, well adjusted young person, who does their personal best in school, has friends, and enjoys life.
Worry about college in a few years.