A bike for city commute - disc brakes, bar-end shifters, tires I'm planning on buying a bike for city commute. 

My commute to work is approximately 12km (7.5 miles) one way.  I live in Vancouver which means:


I'll be riding in rainy weather frequently.
I'll be going up and down hills.
I'll be going through lots of intersections (meaning lots of stopping and starting again).


And I'll be commuting mostly during the rush hour.

Here are a few questions:


Since I'll be riding in rainy weather: a) should I get a bike that has disc brakes?  I read somewhere that they behave better than rim brakes. b) should I get a bike that has hydraulic vs wire brakes?
Since I'll be going up and down hills, I'll be changing gears.  Are bar-end shifters the best choice for this type of riding?  Or are they meant for rides where the gears don't change often.  
What kind of tires should I be looking for?  I figure (intuitively) thinner tires are faster, but since I'll be riding in rainy weather should I opt for thicker tires (more surface area)?


Is there any other thing I should be looking into?
For a city commuter bike, don't bother with disk brakes - go for simple rim brakes. You'll want the reliability over all else. You don't need disks for most types of road cycling, as the limiting factor for grip is likely to be your tyre anyway.

As regards shifters, go with whatever is comfortable for you. I like the combination of brakes and gear levers in the same unit, as you don't need to take your hands off the brakes to change gear. This is very useful in traffic.

I would also recommend touring tyres - offroad tyres lose too much power through rolling resistance, but you want tyres wide enough that you have some comfort and puncture resistance. You could also look into self sealing tyres.