We arrive around 8 AM - and plan to take a train to Florence. What is the best way to do this? Should I or do I need to book in advance - if so, how much time after our arrival? what if plane is late?

Interested in Florence?
We'll send you updates with the latest deals, reviews and articles for Florence each week.
Do not book beforehand. You do not know whether your plane will be delayed or by how much. Just go to the ticket office at Malpensa airport and buy the tickets to Florence.
The first train from Malpensa direct to Florence leaves at 12.22, but there are earlier journeys with a change at Milan Central.
You can get train times and costs from www.lefrecce.it but you must use Italian names for towns: look for Malpensa aeroporto to Firenze.
That is very helpful. Thanks! Since we fly in from the US - term 1 presumably - where do I find the trains? I was getting so confused before - looking like I had to take a bus to the Central Milan station....and then to Florence.
So, you are saying the direct train (no change of trains) departs Malpensa at 12.22 but that there are earlier other trains that will get me from the airport to the central train station where I would change trains (and buy another ticket?) for Florence?
Just follow the signs for trains.
Whether you take a direct train or have a change in Milan Central, you buy tickets at Malpensa all the way to Florence. See the site I referenced for train times.
If your flight arrives on or nearly on time, you will not want to wait for the 12:22 direct train to Florence (stopping, but not connecting, at Milano Centrale). Instead, you'll want to take the first train out to Milano Centrale, where it's a simple connection to the hourly Frecciarossa high-speed train to Firenze SMN. The ticket office at MXP airport will sell you tickets for both legs of this trip (so you won't need to stand in line a second time once you arrive at Milano Centrale).
Perfect. Thanks so much for the help.