there will be no rails on the bottom of the seat.
yes you do
Yes you can but, depending on your frame, you'd need a shim to get the post to fit your frame.
You have to be 13 years old if you are in England but I don't know about other countries.
Five seats, and your grammar is wrong
Faurecia SmartFit Seat
Learn to Pick the Right Car Seat For Your Toddler
How to Choose a Car Seat
One Minute Car Safety Seat Check For Your Child