Okay, so I did a little digging through the park's website and it's most recent newsletters. The first photo is not just the new banding station, but the new "Ecological Research Station"! Apparently it will have the ability to be moved to a different location if the need ever arises.
The second structure (located beside the guard tower/truck gates) will become the park's "staff booth".
The Staff Booth allows TRCA staff to interact with park visitors and monitor their activities, it also provides park interpretation opportunities, provides shelter from the elements and a place to wait for TRCA’s shuttle van. And it will have WASHROOMS!! I can't find any reference to it being used for the trucking activity. I would think the guard tower and gates will remain until 2013 when the dumping activity is scheduled to end.
The last structure is the "Enironmental Shelter".
Incorporated into the meadow at the east end of Cell One will be the environmental shelter. This building will appear sunken into the landscape and open to the wetland. It will be used primarily as a gathering area for school groups during field trips, and provide children with washrooms and a storage area for their belongings. A lookout facing the wetland on the roof of the shelter will create opportunities for nature viewing and interpretation. Cell One is not the bay with the tern rafts (you're right, not much to see there), it's the first marshy pond. Think beaver, mink, turtles, kingfisher, lots of shorebirds etc.
Apparently there are plans to build a fourth structure at the entrance, but I'm not sure if they've found funding for it yet.
If you're really curious, here's a link to the architect's website that shows what the completed buildings will look like (once you open the page, click on slideshow) :
http://www.montgomerysisam.com/projects/tommy-thompson-park-infrastructure
