Yes, I see some merit in your first two points though I could take issue with some details--not being elected, for instance, senators tend to be less partisan--but this third point I don't get at all. First, I don't see how you could possibly know the Senate gives very poor value for money compared to other government bodies that could do the same things it does. The cost of running the Senate is a pretty small fraction of public expenditures. Second, what are these other government bodies? Only the Commons and the Senate have any legislative power, there is no other government body that can do that. I will cite the conclusion from the chapter about the Senate in the well-known basic textbook, Dawson's The Government of Canada, 5th edition, page 303: "There is every reason for the Senate to remain a secondary partner in the Canadian Parliament. There is no reason for it to remain the comparatively unimportant and ineffective body it has become; if it remains so, it must be emphasized, it will be by the Senate's own choice." That's as true now as it was when the book was printed in 1970. The Senate needs a better class of senators, not reform or abolition.
Other government bodies? The only thing even remotely useful that the Senate has ever done is to conduct investigations into major problems in Canadian society. However, a permanent body costing millions of dollars could easily be replaced by using members of the existing bureaucracy to carry out that function. At worst such investigations could be contracted out at a much lower cost than that of running the Senate.
As for the Senate having legislative power, when was the last time it used it effectively? Since for the most part the Senate consists of carefully chosen lapdogs loyal to the government (as Mr. Harper so aptly illustrated with his last three appointments). One of the original concepts of the Senate was to provide some regional representation. There is no indication that the current Senate in any way performs that function.
Given the fact that the Senate no longer performs the function it was intended to perform (if it ever did); and that it is essentially a retirement home for failed politicians and supporters of the party in power; and that it has little real power and seldom uses what power it has; one has to wonder why this institution still exists. It is interesting to note that many nations with Upper Houses including New Zealand, the Netherlands and Sweden, have recently abolished them; then perhaps it is time for Canada to do the same.