Having lived in that area 25+ years ago, my opinions are as follows with the caveat that some of these things may have changed since then:
1) The parking on Dahlia shouldn't be a loss, as nobody parks at that end of the street anyhow - that section of street faces the blank wall of 1 Oak Street's parking garage.
2) The Dahlia/Maple intersection has always been a problem, as Maple is used as a main commuter route to the Macdonald Bridge. I recall many vehicle accidents, some fairly bad, at that intersection. A childhood friend was actually killed crossing Maple Street further down the hill, many years ago. Maple/Pine/Victoria are all fairly steep hills, and with people rushing downhill on a commuter route, I would have concerns whether the proposed signals would be effective enough.
3) Pine is steeper than Maple, so I would not suggest putting stop signs on Pine in the middle of the slope - I recall driving down that hill (and Victoria) in slippery conditions in the winter and not being able to slow down enough to make the turn onto Dahlia, even when approaching it fairly slowly. After awhile, I decided to just not attack those hills in slippery conditions.
4) I don't agree with the person in the article who says the crossing at Victoria is at the crest of a hill. It is fairly steep there, though.
5) Leighton Dillman Park has always been a nice place to stroll. Some of the paths are a little on the steep side, and they never used to keep it ice-free in the winter. I think it would be kind of a shame to mix foot traffic with bikes, if the bike traffic became heavy enough, so I don't think using the park as a cycling route is a good idea, actually. Park Avenue is basically traffic-free, so I think that would be a better route.