+about a million. Don't lug anything around that you don't need to. Leave a pair of shoes, a towel, soap, shampoo, razor, and/or anything you need on a regular basis at work.

I have walked most of a marathon in a pair of mountain bike shoes and walked many miles in the dark in mountain bike shoes. While not the most comfortable shoes, you can walk for quite a ways in them without ill effect. I've worn worse...and better.

Finally, there is absolutely nothing wrong with riding in stop and go traffic using a clipless pedal. I've done it for most of 20 years. They are tons better for stop and go traffic than clips and straps because, for the most part, you don't have to flip the pedal up to engage it. If you get your foot on the pedal, you'll get it clipped in place with a clipless pedal. Toe clips are a pain to use anywhere...I rode those for most of the previous 10 years and haven't missed them. And, no, I wouldn't even consider a platform pedal. I find them hard on my knees.