Regarding the 4-way tie in Bronze, I was thinking of having a mini-tourney.
Normally in a tie-break situation we ask the 2 people tied to play two games on the same map, alternating who goes first. If someone wins both then they are the winners. If not, then they play another two games on a different map and so on until one person wins two in a row.
In this case, we could do that and then have the two winners go on to face each other for first and second place, and the two that were defeated could fight it out over who gets third place and the promotion. It could mean quite a few games are required though (at least four).
I'm not altogether sold on the assassins or doubles ideas since it's a 1v1 competition and I think it should be decided with 1v1's.
Alternatively, we could always split the points 4 ways and leave it at that, but then there would be no guaranteed promotions from bronze next season and no one would get the banner.