I'm currently in grade 11 looking to go into Medrad (my first choice) but I'm wondering if they look at grade 11 marks? Do I need extra curriculars and a lot of volunteering? I currently have an 89 average overall this year but I'm just worried how competitive and hard to get into it is.

no it's not. The BS that you hear about engineering and business admissions for example being super high 80s are not accurate as those are interim admission averages. The averages will go down for sure when the large wave of offers come out (I think most of them have gone out after midterms for semester 2 were received)