Context: I have an Aeroplan ticket YYZ-GRU at the end of December, then a domestic flight inside Brazil on another airline (on a separate ticket).

Questions:
+ Is it possible to thru-check my bags from Toronto if I have two separate tickets?
+ Are there airlines in Brazil I should favour over others to make this easier? I haven't bought my domestic Brazil ticket yet, so there's still some flexibility.
+ If I end up on separate tickets with no interlining, does anyone with experience at GRU have a sense of how much time I should leave myself for a safe connection? (collect bags, immigration, check-in again, security, etc.)

Thank you!