We play BC twice this year. How does that season series tiebreaker work? If we lose the 2nd game in BC, who wins the season series? Is it points between the 2 games? If so, as long as the Bombers lose by 9 or less in BC we win the season series, or no?

I'm fairly sure you are correct

BC would need to outscore us by 11 in the next game or we could just win.

Let's not worry about tiebreakers with BC let's just win more games than them. Shouldn't be too difficult a task, that BC team isn't the same one they were. 

The tie breaker would be per cfl.ca

 

has scored the higher net aggregate of points (i.e. points scored for less points scored against) in all games played against all of the other tied Club(s), 

 

So yes, you are correct.

Just win more games and beat them in week 16. No tie breaker needed.