How long does it take go to St Tropez from Nice if I were to take a train?

You can take a bus to Freijus (1hour 15 minutes, 20 euros) and then a taxi or another bus (almost 2 hours - it's a local bus, 9.5 euros) from there to St. Tropez.

Taking a taxi directly from the airport will cost you about 270 euros.

I can't recall the name of a nearest train station to St. Tropez.

Going by plane is the longest way(not the fly,but all the roads to and from the airports),by bus or train it will be about 3-4 hours and you can see a lot of beauties during the trip.By boat it's ,of course, the most special way,but you can't see nothing but watter (yeah,the Mediteranean and it means a lot) and I don't know nothing about the hours of departs or arrivals,neither the prices.However,the French Riviera is a gorgeous place,a "must see" one,so Bon voyage!