I would suggest that you join biochem only if you are genuinely interested in the field of biochemistry. 2nd year biochem is the same for alll biochem students (i.e. core and specializations) and about the labs, it's kinda true. You only have to take the second year lab course 2L06, but not the 3rd year one, only specialization students have to take that one. 2L06 gives you both lab experience and teaches you how to do research, write reports, and papers. The prof, Felicia Vulcu also tries to bring in guest lectures to try to show what kinds of careers are open to students with a biochem degree. As for co-op, you apply after second year, and if you get selected then you finish your degree in 5 years due to the two work terms that are added.
THe biochem courses won't really have too much chem in them, but other classes like orgo and phys chem are mainly chem based so you should at least be able to do those.
Hope that helps