Pizza/Baking Stone Questions

i'm thinking of adding a pizza stone or baking stone to my new bluestar rnb (all gas). a few questions:
1. do i put it on the bottom floor of the oven or on the bottom rack (my hope is to leave it in there all the time?
2. does it add significantly to the amount of time it will take the entire oven to heat up? i do a good amount of high heat roasting - 500 degrees. can it take that?
3. pizza stone or baking stone? or are they essentially the same?
3. what other quirky thing do i need to know?