Welcome to Alaska. Hope you enjoy it.
To answer your first question on cruise lines. Princess is the most popular and set up. BUT..... when you go on a cruise line vacation, you are herded like cattle. You get to see a lot in a short time but, have your walking shoes on. Another alternative is to either drive up which is good or take the Alaska ferry which is better for sight seeing. The ferry will finally drop you off at Haines and you can drive the the rest of the way, if you take your car on the ferry. The ferry also stops at a lot of places on the inside passage which is fantastic if you want to get off and sight see some. It all depends on which ferry package you get. If you want to drive up to here, get the "Mile Post". It will tell you everything about everyone and everything on the drive up here. It describes both ways, Alberta and British Columbia. If you have your vehicle, you will not have to take the train unless you absolutely want to. You can see just about as much if not more from the road system as you can on the train, and if you want to make time to reach somewhere you really want to see, you can do it in your vehicle.
It all depends on what you want and how much time you have. You can even rent class C RV's to drive around and see stuff. Don't know how much they cost to rent but I can tell you Princess cruises aren't cheap. Just another alternative to think about. Fly in and rent a RV.
WD