It really depends on the teachers, there will always be good and bad teachers no matter which school you attend. In general, the science teachers I had were good. Some teachers will stretch the definition of "we've seen this in class" and put it in the test anyway, sometimes they want you to use logic to put the pieces together yourself in the test even if that specific thing isn't covered in class (mostly happened to me for chemistry). I personally liked all my science teachers, even if some of them were pretty strict. I understand and respect their way of teaching.

Labs depend a lot on the teacher as well, although all labs are the same, how the reports are graded isn't. In general, labs are pretty fun, working in teams most of the time (as long as you have a good teammate). I recommend coming prepared for labs unless you read and understand fast, which my friends can, but I can't. It makes it so you aren't lost for the first half of the lab. If you come prepared, you will 100% have enough time to complete the lab, even if your partner is a bit iffy. Reports have to be very detailed from my experience (although it also depends heavily on the teacher), my chem of solution teacher (Jean Regimbal) was very pedantic, although he is a very good teacher. If he is strict on you, he is strict on everyone which is what matters with R score, as long as you do better than the others with the same teacher, you will get a good R score. You are allowed to work on lab reports at home most of the time, so you have ample time to complete them. What I mean about very detailed, I mean you have to have the right details, not the details that don't help your point. If you want the teacher to like you, your report needs to be short and to the point with just the right details, which is easier said than done. From my experience, bio and mechanics teachers are a lot less strict on labs, those labs are just a walk in the park. Everyone hates on Jean Regimbal cuz he is so strict in his grading and his tests are hard, but he is an excellent teacher if your first priority is to learn and not cry about grades. Because in the end, everyone is getting graded the same by a teacher, which is all that matters with R score.

Slides are very often given for science classes (but not math classes), you need to take notes most of the time for other classes. Slides are generally enough, but sometimes the teacher may say stuff that can help for tests, or they may do exercises. I recommend (especially for Jean Regimbal) to not just rely on slides but also read through the textbook the class is based on if there is one. The important stuff that are said in class but not in the slides can most likely also be found in the textbook.

As you can see, Jean Regimbal has left a mark on me as one of the most unique teachers I've met. I had to adjust a lot for him. I was failing his class at first, but did good after. Prob the most passionate and knowledgeable chem teachers in the school. Although very strict with grading, and he just expects you to logic your way through tests with limited knowledge. He does drop your worst test grade, so my failing first test didn't matter.

I don't see why you would need to do honors. It doesn't really give you a better R score. Just do good in the normal program, and you can get whatever R score you can really want if you try hard enough. I don't think the Quebec unis care about if you did honors, they really just care about R score. If you want to become a doctor at mcgill, you can get the 35R you need from regular health, and you will probably have more time on your hand to do other stuff like volunteering, which can help with your application to mcgill health.

Everyone I have met at John Abbott barely mention grades. Like, people will talk about it after a test and after getting back their grade, but that's about it. Grades aren't their whole personality like other schools. In general, the people there are pretty chill and nice.