The train ride is really nice -- about 3-1/2 hours. It's more comfortable than the bus -- you can get up and move around, and there is food (you have to pay for) if you want it. (And restrooms, of course). The bus is...well, a bus. The bus trip is longer -- as the bus is slower. Scenery from the train is awesome.
Did you arrange your air through Princess? You could also arrange connections to the train through them. Then they'll meet you at the airport, get you to the train and on your way, and deal with your luggage all the way to the ship -- a VERY nice bonus. It'll cost you, of course, but might be the easiest way to approach it.
Sorry..I don't have a schedule or links, but you can go to Google, type in Anchorage, get there, and ther are links to the train schedule.
I'm flying to Anchorage on August 28, staying 2 days, taking the train to Seward, and boarding the Island Princess. I booked through Princess, saving a bunch on the plane, but paying for the transfers from airport to Anchorage hotel, 2 nights there, and train to Seward -- $350 (approx) per person. Which is quite a bit cheaper than I could arrange all that on my own.
We took the train ride also and it was wondeful! We booked it 'online' ourselvesand we paid a little extra to sit in the dome carraige. http://www.akrr.com/passenger/seward.html
We also booked to stay in the Windsong lodge in Seward for the night prior to our cruise and they provided transport to the train station also. http://www.sewardwindsong.com/
Hope you have a wonderful time!