About one month before your tour starts, you will find a list of all the hotels on your tour in your tour account. Included will be very specific directions about options to get to Padua - from the airport, from Venice proper, and from Milan. All the options are quite easy.
I spent two days in Venice before the tour and took a train from there to Padua. I also had an extra day in Padua. I highly recommend that you build in at least an extra day before the tour. This relieves the stress of getting to the first tour meeting on time. Flying in on the same day as the tour starts is risky.
At the end of the tour, the guide will help organize transportation to Milan or the Milan airport, or whatever. You can often share a shuttle with others to keep the cost down.
Village Italy was a great tour. If this is your first RS tour, you are in for a treat! (It was my 8th tour.)