Apart from the (insanely worded) rule requiring you to ride on the "extreme" right hand side of the roadway, you have the same rights as cars in terms of road position. That includes pulling into the left-hand lane in order to perform a left turn. If this intimidates you (and hell, turning left from Sherbrooke onto St Denis intimidates the shit out of me some days) you are also able to "box" the intersection like a pedestrian would do: ride over to the opposite side then wait on that corner for the lights to change. That approach is a lot safer and less harrowing on busy roads.

As for saddle-sore, expect it to go away after about a week if you're riding every day. If it gets too much, take a rest day. If it doesn't go away, consider a different saddle.