First of all, we try to tackle all questions, so please don't feel silly.
The best place to wear your pedometer, is at waist level, in alignment with your knee - it usually doesn't matter which side, but with the limp you mentioned, you may want to try it on both sides to see if there is a difference.
Some pedometers come with a strap, so they won't fall off or get lost. If your new one doesn't have this you can use a safety pin and a shoe lace!
Here is a great SparkPeople article on how to choose and use a pedometer: www.sparkpeople.com/resource/fitness_artic
I will check on how to measure your gait, and get back to you. Good question!