I think there were originally 6 through platforms, reduced to 4 in the late 80s rebuild. I'd have thought these would be reinstated if it was possible. There's plenty of room to reinstate some extra East-facing bays but the need is for through platforms or Westbound bays.
The Tod curve services will mostly run through Vic towards Salford and beyond, to various destinations. At least one will be a Blackburn to Clitheroe via Burnley, Todmorden, Manchester, Bolton and Blackburn again! Circular services can cause issues at times of disruption, one of the reasons the Circle line no longer runs as such.
Before the redevelopment of Manchester Victoria in the early 1990's to accommodate the arena there used to be 6 through platforms (11-16) and the original plans was to have 6 through platforms (2 under the arena) in the redevelopment but I suspect due to cost this was scaled back to only the 4 that we have now.
As to additional platforms at the east end there is no room for them as the Metrolink has taken all the space up.
As to the Exchange this land has been sold and is currently being redeveloped into office blocks to accommodate Salford City Council new head quarters, before anyone queries this Salford starts just the other side of Trinity Way which is the road that you access the arenas car park from.
As to increase of capacity in extra platforms there is going to have to be some "blue sky" thinking as there is limited space, the best and probably only way to do this is to have Victoria as a through station and trains only stopping for a minute or two to set down and pick up passengers.
There are talks of re-opening the two disused platforms at Salford Central for terminating trains from the West to open up more room at Victoria, but if this is to happen it is probably going to be quite a while off, but also if you look at how the overhead stanchions that have gone up at Salford Central it seems more plausible that this will happen as they have ample room to get track and overheads up on the current stanchions.
I use to be a Train Recorder at Manchester Victoria West in the early 90's and watched them build the station, still to this day I still work in the area. Kind of my home away from home.