1. Speed: If you haven't been biking a lot, you might want to take it easy so you can turn around and do it the next day and the next, and so forth. If you can only do 11 mph tops now, take a little off that at first. You will probably want to push the pace as you get used to the distance just to save time and increase your fitness level. On the other hand, some take it slow simply because they need to look/smell nice and don't have the opportunity to shower at work.
2. You're on the right track with the stuff you will need. Will you be riding at night much? Is the bike path lit? People will chime in with light recommendations if we understand your needs a little better.
Have fun with your ride!