Welcome to Slowtalk, Julie.
Have you seen
Arriving and leaving from Milan on the main Slowtrav database?
I like the bus from the airport to the train station. It is equipped for luggage- someone loads it into the bottom of the bus for you. There are 2 busses, both leave from aprroximately the same place, the exit to your right as you leave the baggage claim. One requires purchasing tickets in the terminal, the other allows you to buy tickets at the bus from the driver. There are good instructions above each baggage claim, and you'll probably have enough time to memorize them as you wait for your luggage to appear. The bus is an odd sum- either 4 or 8 or 9 Euro, I think. I remember thinking on Christmas night that constantly having to make change must make the driver crazy.
The ticket windows and machines are around the corner from where the bus leaves you at the central train station. Or you can forget this, as I always do, and take the escalator (if it's working!) upstairs, then go to the other escalator to your left and take it down to the ticket sales area.
I've only taken the train from Malpensa to Cadorna once, and that was to meet a friend at the airport and then change continue into Milan to meet other friends. I remember thinking I wouldn't want to do it jetlagged and hauling a lot of luggage, but others seem to swear by it from what I've read here.
There are ATMs at Malpensa, easily visible when you leave baggage claim.
I'm sure there must be a manned luggage check area at the train station, but someone else will know for sure.