Congratulations on your new position Clichty.

1) For breakfast Clitchy you could try a meal replacement bar or something like a meal replacement shake (I blend my own). I am not a low carb/no carb type of person, but certain carbs can make you feel slow or sluggish. I prefer fruits or vegetables to something highly processed like a danish or donut before a long ride. After you get to work you can probably pig out a little.

2) For tires I agree with the other poster to ride what you've got for now. After commuting you may start to feel differently. If you are getting more flats or something look into the Gatorskins. You also may want something faster than what you currently ride, or something more comfy. But thier is usually an opportunity cost involved.

3) For backpacks over that distance I'd probably look towards the ones with an internal frame and probably a mesh back and (relatively) lightweight. Also, evaluate what you really need to bring to work versus what you can store their. At that distance I would be looking along the lines of a rack also though.