I have had good luck with Specialized Crossroad tires for the rear and specialized Hemisphere for the front. 1000 miles of street riding they still look new and no flats.
I run the super flash and 1/2 watt blaze day and night. I ride all street to work and the Super flash is bright enough to catch most people's attention in late afternoon sun.

I'm trying to get a less is more attitude because I found my self riding a pack mule with the trunk bag. my seat bag has the following:
Small cheap multi tool
Cheap plastic Tire levers
patch kit.
Seat cover (I have a brooks on one and leather Terry's on two).
Sometimes I carry a inner tube if it is going to be a long ride.

I really like my Alien II multi tool but it is big, heavy and bulky. Touring it is on the bike. For commuting I have never needed it so I got the cheap multi tool that is 1/8 the size and weight.
Cell phone. I can always call the Wife or work buddy sag wagon if it is more then a mile walk in.

I keep a frame pump on all my bikes. CO2 is nice but you have one shot And on a large mountain tire it may not get it full. If you didn't get the leak fixed you are SOL. I like the Topeak Morphs the best. Built in gage, hose so you don't stress the tire valve and it has a flip out foot holder.

Head light...Very few small lights that will do the job. Unless you are going slow you can out run them if you don't have a path that is lit with street lights. I run a Cygo lite Night Rover in the winters when I will be commuting in the dark. Worth all 2+lbs for the 16 watts of light. Expect to spend at least $100 a light. I'm to the point that my main commuter may get a Dyno hub. $160 you can get a built dyno wheel from http://www.velo-orange.com/shdyhubwh.html