(Switching back to sane compass directions, not Kitchener's)
There shouldn't be plans for a North side platform there. The medium term plan is to move the train station to King St, at which point, this whole section at Weber will be well east of the station. We won't need more than a single platform until the move, as I don't see anything resembling frequent service starting until 2020 at the earliest, which is the horizon at which the station will move to King.
Afraid not.
The Margaret St overpass was demolished when structural design deficiencies were found. They have recently approved funding and construction on the replacement, but have approved an overpass that will only support 2 tracks underneath. 3 tracks were considered, however without firm details of plans for highspeed, or even rapid service, Kitchener (which is footing the entire bill) could not justify the extra expense.
Fun fact: Construction on the replacement span starts today