I'm curious about the current use and accessibility of the Baptistry to the residents of Florence today. Can the common Joe still be baptized here and when? It seems so packed with us tourists.
No, not everyone gets baptized there anymore but if you really want to do it, the common person can do it.
I believe having looked it up not too long ago that they do mass baptisms like once a month. So you just need to plan for it ahead of time to get in. They close it to visits for a morning to do it.