AMA Request: Someone who has been on America's Funniest Home Videos (AFV)

Everytime I watch this show the audience seems so fake and plastic.

Do they tell you to keep a constant perma-grin on? Do they seed the audience with actors/models? Do the winners know in advance that they won? (they never seem to have an honest reaction to the $) How many shows do they tape with you in it? (i.e. do you just change clothes?) What is Tom B. like? (host)