Regarding DRL, at least the per km cost of Sheppard and of Spadina extension can be used for estimates.
Really? Again, I would think that the biggest cost, by far, would be in expropriating and tunnelling under expensive and more densely-covered downtown land.
That said, I have no beef with the DRL. I'm just not sure it's a very good cost comparison.
St Clair does not cross the RH line: it terminates just east of Mt Pleasant Road and starts again well east of DVP. Could concider a stop at Leaside Bridge: bus connections to Overlea and Laird.
Bus connections aren't quite the same, mind you -- everywhere else you would be connecting to LRT (or stubway). Bears some thinking about. (I really like nfitz's idea but, well, like he says: 2100...).
A stop south of Bloor (Dundas or Queen) may be considered, but it will be for trips between the north and the south-east, not a downtown-relief stop. Passengers who have travelled on streetcars as far as Broadview are unlikely to switch to GO for a short final chunk of their trip.
Right. Again, and I hope I have not been unclear on this point, the RH LRT would relieve the north end of the Yonge line, not the south end.
By all accounts, demand in the north end (Eglinton north to, say, 7) exceeds the Yonge line's capacity. The RH LRT would be an express eastern configuration -- am I making unwarranted assumptions about technologies? is "LRT" the wrong thing to use for an express line that only stops at major concessions? -- anyway, would be an express north-south line on an easterly configuration that would relieve the overcrowded Yonge line using the least expensive and most efficient means (i.e. don't tunnel, don't expropriate, use the ROW that's already there).
Then riders Eglinton and south would be able to "get seats", an extremely important transit planning goal,
and this would have been accomplished by giving transit riders alternative options rather than encouraging them to switch to cars, an obviously less important transit goal but still one worth pursuing.