700c double wall, cassette for rear hub
Kevlar puncture guard tyres like the Marathon Plus are a bit slower and heavier than non-protected tyres. However, since you will get a flat tyre every year instead of every 2 weeks, you will no longer need to time your trip to arrive 10 minutes early just in case you get a flat. So in the end, it makes the trip faster if you need to arrive at a specific time. And the Marathons plusses last forever.
Clipless pedals and shoes?
Road-bike clips/shoes are not designed for traffic light stops or walking. MTB clips/shoes are much better.
SPD are the standard but I don't like them.
Time Atac (like the Aliums which retail here in europe for about 35€ a pair) are a lot better, clip-unclip is instinctive and extremely fast. Also last forever.
Avoid Crank Bros at all costs. They will break and you will die.
If you will climb, get a good assortment of granny gears.
If you won't this is less important.
Note most bikes are geared way too long. Having enough gears to run up to 50 kph isn't very useful unless you race. Having a good assortment of gears suited to your speed, your hills, and your power/weight is much better.
Gear hubs resist much better against dirt, corrosion, salt, etc, but are expensive.
Handlebars (e.g. flat or dropped)?
In traffic you need to look far ahead, and also look back over your shoulder pretty often. Drop bars make this harder. Also your hand should always be ready on the brake just in case. So, I prefer straight bars.
Frame (size, shape, material)?
If it rains, yeah. From the last time I visited Toronto, definitely.
Rack and pannier at the rear ; no backpack (makes you sweat).
Lights (very important).
For commuting what determines the average speed is :
1- choice of route (safe and slow or fast and dangerous, your choice, you must explore around to find a fast and safe route)
2- traffic lights
In a typical city 20kph average is already very fast, you can't go much faster unless you burn all red lights and generally behave like a suicidal maniac. That's much faster than a car at rush hour, or a bus, though...