The planning and engineering work for Transit City is not being done in house. Various transportation consulting and engineering firms are working on the individual lines. Transit City is actually moving faster than most transit projects have in the past, thanks mostly to the expedited EA process.
Planning costs can't just come out of "TTC cash", if there even is such a thing. "TTC cash" barely covers the cost of operating and maintaining the existing system. All Transit City EAs and engineering design is coming from capital funding grants from the upper tiers of government. And as a result, the detailed design phase could not proceed until the money was provided, not to mention that the EAs aren't even complete to allow for detailed design.
Just because St Clair has a right of way down the middle of the street, it doesn't mean that its design can be cut and paste on top of any other street, as Chuck has mentioned. Every street has different widths, different traffic conditions, different curb cuts and site entry points, different environmental conditions, different built environments... need I go on?
Finally, I think you're extremely oversimplifying the planning process. Condos and homes don't just go up in a year, they take just as long, if not longer, to go through the planning, approvals, and construction process. The condos you see going up today probably started design and approvals four or five years ago. Take a gander at the Projects & Construction forum and look at the first post in the threads of projects now under construction. You'll notice they date back to 2005 or 2006. Then remember that the project has probably been in the works for a year or two before that before we at Urban Toronto found out about it.