Well first year at McMaster, students in Life Science would have to take 30 units (10 courses)- Often includes the two general chemistry, two psychology/kin, two biology, calculus, physics, and electives. After first year, life science students select what they want to major in. Here there are so much options to choose from including Honours Biology, Biochemistry, Math and Physics, Geography, Honours Psych etc.
Different majors have different average cut-off and are competitive. If you maintain at-least a 6.0 (C+) GPA, you can get into Honours Life Science Major at Mac. I think 4.0 you can enrol in a three year Major (4.0 in 12.0 scale). Other majors usually require high averages to get in and are competitive (Honours Life science major and a few others if you have 6.0 your guaranteed a spot)
I think Honours Life Science has only one specialization which is Origins. To be honest, I don't think there is much 'medical' focused majors (unless your in Health Science program). Biochemistry and Biology has a variety of specializations!
Remember, your first year is just an entrance year. Second year everyone diverge into different majors and each major usually has specialisations associated with it. You should look at the majors offered here and make your decision.
Honours Life Science is a major. I would view it differently from the first year life science program (That's more of an entrance program where you get an year to decide what you want to major in)!
In terms of medical school prep. You can take the prerequisites from most program (Honours Life Science let's you take the most # of electives so that's something to consider). There is no program that focuses on medicine (I think), but you can certainly take virology, health based courses if you have room (again being in Honours Life-science gives you enough room to take them!)
Hope that makes sense! Good luck